error : dragStartMode cannot be resolved

Hi, I made a small modification to an aplication that was working fine, (I just add new labels) but after I tryed to test how the changes will look this error began to show:

[ERROR]
Errors in ‘jar:file:/D:/Proyectos/EclipseWorkspaces/Verificadores/hebpvm2/WebContent/WEB-INF/lib/vaadin-6.8.9.jar!/com/vaadin/terminal/gwt/client/ui/VDragAndDropWrapperIE.java’
[ERROR]
Line 55: Referencing method ‘com.vaadin.terminal.gwt.client.ui.VDragAndDropWrapper.html5DragStart(Lcom/vaadin/terminal/gwt/client/ui/dd/VHtml5DragEvent;)’: unable to resolve method
[ERROR]
Line 28: The method getDragStartElement() of type VDragAndDropWrapperIE must override or implement a supertype method
[ERROR]
Line 31: dragStartMode cannot be resolved
[ERROR]
Line 31: HTML5 cannot be resolved
[ERROR]
Line 50: The method hookHtml5DragStart(Element) of type VDragAndDropWrapperIE must override or implement a supertype method
[ERROR]
Line 60: The method hookHtml5Events(Element) of type VDragAndDropWrapperIE must override or implement a supertype method
nov 06, 2013 4:23:10 PM com.vaadin.terminal.gwt.widgetsetutils.ClassPathExplorer getPaintablesHavingWidgetAnnotation
INFO: Searching for paintables…
nov 06, 2013 4:23:16 PM com.vaadin.terminal.gwt.widgetsetutils.ClassPathExplorer getPaintablesHavingWidgetAnnotation
I

I didnt change anything but the labels, and the proyect was working fine, I dont know what is happening, someone have more info about this?