Error when use service builder in vaadin portlet

Hi everyone
I have a problem when using service builder in vaadin portlet. I have builded file service.xml and generated some class but when i run this portlet i have error

[b]
Vaadin is running in DEBUG MODE.
Add productionMode=true to web.xml to disable debug features.
To show debug window, add ?debug to your application URL.

14:15:36,342 INFO [PortletHotDeployListener:385]
1 portlet for demo-portlet is available for use
14:15:37,519 INFO [PluginPackageUtil:1081]
Reading plugin package for demo-portlet
Mar 6, 2011 2:15:37 PM org.apache.catalina.core.StandardContext reload
INFO: Reloading this Context has started
14:15:50,888 INFO [AutoDeployDir:167]
Processing demo-portlet.xml
14:15:50,902 INFO [PortletExplodedTomcatListener:59]
Modifying portlets for E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\deploy\demo-portlet.xml
Warning: log4j.properties modified in the future.
Copying 1 file to E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\webapps\demo-portlet\WEB-INF\classes
Warning: logging.properties modified in the future.
Copying 1 file to E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\webapps\demo-portlet\WEB-INF\classes
Warning: context.xml modified in the future.
Copying 1 file to E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\webapps\demo-portlet\META-INF
Warning: _servlet_context_include.jsp modified in the future.
Copying 1 file to E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\webapps\demo-portlet\WEB-INF\jsp
14:15:53,196 INFO [PortletExplodedTomcatListener:65]
Portlets for E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\deploy\demo-portlet.xml modified successfully
14:15:53,197 INFO [BaseExplodedTomcatListener:45]
Copying file E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\deploy\demo-portlet.xml to E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\conf\Catalina\localhost
14:16:15,694 INFO [PortletHotDeployListener:420]
Unregistering portlets for demo-portlet
14:16:15,713 INFO [PortletHotDeployListener:449]
1 portlet for demo-portlet was unregistered
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
14:16:16,669 INFO [PluginPackageUtil:1081]
Reading plugin package for demo-portlet
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
14:16:17,323 INFO [PortletHotDeployListener:226]
Registering portlets for demo-portlet

Vaadin is running in DEBUG MODE.
Add productionMode=true to web.xml to disable debug features.
To show debug window, add ?debug to your application URL.

14:16:17,494 INFO [PortletHotDeployListener:385]
1 portlet for demo-portlet is available for use
Mar 6, 2011 2:16:27 PM org.apache.catalina.startup.HostConfig checkResources
INFO: Undeploying context
[/demo-portlet]
14:16:27,580 INFO [PluginPackageUtil:1081]
Reading plugin package for demo-portlet
14:16:27,599 INFO [PortletHotDeployListener:420]
Unregistering portlets for demo-portlet
14:16:27,600 INFO [PortletHotDeployListener:449]
1 portlet for demo-portlet was unregistered
Mar 6, 2011 2:16:27 PM org.apache.catalina.startup.HostConfig deployDescriptor
INFO: Deploying configuration descriptor demo-portlet.xml
Mar 6, 2011 2:16:27 PM org.apache.catalina.startup.HostConfig deployDescriptor
WARNING: A docBase E:\HOCKI8\DO AN\LIFERAY\Liferay 6.1\liferay-portal-6.1.0\tomcat-6.0.29\webapps\demo-portlet inside the host appBase has been specified, and will be ignored
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
14:16:28,613 INFO [PluginPackageUtil:1081]
Reading plugin package for demo-portlet
Loading file:/E:/HOCKI8/DO%20AN/LIFERAY/Liferay%206.1/liferay-portal-6.1.0/tomcat-6.0.29/webapps/demo-portlet/WEB-INF/classes/service.properties
14:16:28,863 INFO [PluginPackageUtil:1386]
Checking for available updates
14:16:28,865 INFO [PluginPackageUtil:1430]
Finished checking for available updates in 1 ms
14:16:29,174 INFO [PortletHotDeployListener:226]
Registering portlets for demo-portlet

Vaadin is running in DEBUG MODE.
Add productionMode=true to web.xml to disable debug features.
To show debug window, add ?debug to your application URL.

14:16:29,356 INFO [PortletHotDeployListener:385]
1 portlet for demo-portlet is available for use
14:17:56,667 ERROR [PortletServlet:96]
javax.portlet.PortletException: java.lang.NullPointerException
javax.portlet.PortletException: java.lang.NullPointerException
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.handleServiceException(AbstractApplicationPortlet.java:1349)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.handleRequest(AbstractApplicationPortlet.java:487)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.doDispatch(AbstractApplicationPortlet.java:716)
at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:100)
at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:92)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:67)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:80)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at com.liferay.portlet.InvokerPortletImpl.invoke(InvokerPortletImpl.java:643)
at com.liferay.portlet.InvokerPortletImpl.invokeRender(InvokerPortletImpl.java:778)
at com.liferay.portlet.InvokerPortletImpl.render(InvokerPortletImpl.java:430)
at org.apache.jsp.html.portal.render_005fportlet_jsp._jspService(render_005fportlet_jsp.java:1395)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:67)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:80)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at com.liferay.portal.util.PortalImpl.renderPortlet(PortalImpl.java:3966)
at com.liferay.portal.util.PortalImpl.renderPortlet(PortalImpl.java:3925)
at com.liferay.portal.util.PortalUtil.renderPortlet(PortalUtil.java:1253)
at com.liferay.portal.action.RenderPortletAction.execute(RenderPortletAction.java:85)
at com.liferay.portal.action.UpdateLayoutAction.addPortlet(UpdateLayoutAction.java:258)
at com.liferay.portal.action.UpdateLayoutAction.execute(UpdateLayoutAction.java:209)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:161)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at com.liferay.portal.servlet.MainServlet.callParentService(MainServlet.java:522)
at com.liferay.portal.servlet.MainServlet.service(MainServlet.java:499)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:67)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.servlet.filters.strip.StripFilter.processFilter(StripFilter.java:278)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.servlet.filters.gzip.GZipFilter.processFilter(GZipFilter.java:120)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:197)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.servlet.filters.sso.ntlm.NtlmPostFilter.processFilter(NtlmPostFilter.java:81)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.sharepoint.SharepointFilter.processFilter(SharepointFilter.java:78)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:121)
at com.liferay.portal.servlet.filters.virtualhost.VirtualHostFilter.processFilter(VirtualHostFilter.java:201)
at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:48)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:175)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:87)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:738)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:100)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:155)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:87)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:80)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at com.liferay.sampleservicebuilder.service.impl.FooLocalServiceImpl.addFoo(FooLocalServiceImpl.java:59)
at demo.DemoApplication.init(DemoApplication.java:27)
at com.vaadin.Application.start(Application.java:549)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.startApplication(AbstractApplicationPortlet.java:753)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.handleRequest(AbstractApplicationPortlet.java:400)
… 98 more
14:17:56,718 ERROR [render_portlet_jsp:154]
java.lang.NullPointerException
at com.liferay.sampleservicebuilder.service.impl.FooLocalServiceImpl.addFoo(FooLocalServiceImpl.java:59)
at demo.DemoApplication.init(DemoApplication.java:27)
at com.vaadin.Application.start(Application.java:549)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.startApplication(AbstractApplicationPortlet.java:753)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.handleRequest(AbstractApplicationPortlet.java:400)
at com.vaadin.terminal.gwt.server.AbstractApplicationPortlet.doDispatch(AbstractApplicationPortlet.java:716)
at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:100)
at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:92)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:67)
at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:80)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
[/b]
I don’t know how to solve this problem ,Please help me
thanks