Appfoundation Error while using Authentication module

Hi I am extremely new to vaadin.
Recently i started using the appfoundation add-on for View handling and Authentication. I have set up my persistance module as suggested in the appfoundation documentation. But when i try to register a new user i keep getting the following error. I am clueless as to what to do. Please help me out.


Jul 12, 2012 1:00:36 PM com.vaadin.Application terminalError
SEVERE: Terminal error:
com.vaadin.event.ListenerMethod$MethodException: Invocation of method buttonClick in com.example.meetrbus.ui.RegisterView$2 failed.
	at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:530)
	at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
	at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219)
	at com.vaadin.ui.Button.fireClick(Button.java:567)
	at com.vaadin.ui.Button.changeVariables(Button.java:223)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1460)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1404)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1329)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:761)
	at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
	at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Object: org.vaadin.appfoundation.authentication.data.User@6ad8bf is not a known entity type.
	at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:4176)
	at org.eclipse.persistence.internal.jpa.EntityManagerImpl.persist(EntityManagerImpl.java:451)
	at org.vaadin.appfoundation.persistence.facade.JPAFacade.store(JPAFacade.java:218)
	at org.vaadin.appfoundation.authentication.util.UserUtil.createUser(UserUtil.java:104)
	at org.vaadin.appfoundation.authentication.util.UserUtil.registerUser(UserUtil.java:69)
	at com.example.meetrbus.ui.RegisterView$2.buttonClick(RegisterView.java:101)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)
	... 27 more