Eclipse error with activiti designer

[hannibal80]

Hello all,
I'm new to activiti and I'm trying to design some processes but I'm having problems.

My pc has Win7 64bit.

I fresh installed Eclipse Juno, 4.2.0.

Then I followed this instructions http://www.activiti.org/userguide/#eclipseDesignerInstallation and, after starting eclipse as Administrator, I opened a new Activiti Project.
After that, in the root directory of the project I added a "diagrams" folder and, inside it, I made a new file saved as "first-diagram.bpmn".

Now, as I try to put anything in the diagram (as StartEvent, UserTask, etc) I receive errors from eclipse.

Here one of them.

Message:

Problems occurred when invoking code from plug-in: "org.eclipse.ui.views.properties.tabbed".
‍‍‍

Exception stack trace:

java.lang.NullPointerException
   at org.activiti.designer.property.PropertyDiagramSection.refresh(PropertyDiagramSection.java:99)
   at org.eclipse.ui.views.properties.tabbed.TabContents$6.run(TabContents.java:217)
   at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
   at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:49)
   at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
   at org.eclipse.ui.views.properties.tabbed.TabContents.refresh(TabContents.java:220)
   at org.eclipse.ui.views.properties.tabbed.TabbedPropertySheetPage$SelectionChangedListener.selectionChanged(TabbedPropertySheetPage.java:222)
   at org.eclipse.jface.viewers.Viewer$2.run(Viewer.java:164)
   at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
   at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:49)
   at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
   at org.eclipse.jface.viewers.Viewer.fireSelectionChanged(Viewer.java:162)
   at org.eclipse.jface.viewers.StructuredViewer.updateSelection(StructuredViewer.java:2188)
   at org.eclipse.jface.viewers.StructuredViewer.setSelection(StructuredViewer.java:1725)
   at org.eclipse.jface.viewers.Viewer.setSelection(Viewer.java:394)
   at org.eclipse.ui.views.properties.tabbed.TabbedPropertySheetPage.setInput(TabbedPropertySheetPage.java:736)
   at org.eclipse.ui.views.properties.tabbed.TabbedPropertySheetPage.selectionChanged(TabbedPropertySheetPage.java:555)
   at org.eclipse.ui.views.properties.PropertySheet.selectionChanged(PropertySheet.java:365)
   at org.eclipse.ui.internal.e4.compatibility.SelectionService.notifyListeners(SelectionService.java:140)
   at org.eclipse.ui.internal.e4.compatibility.SelectionService.access$3(SelectionService.java:137)
   at org.eclipse.ui.internal.e4.compatibility.SelectionService$1.selectionChanged(SelectionService.java:72)
   at org.eclipse.e4.ui.internal.workbench.SelectionAggregator$2.run(SelectionAggregator.java:111)
   at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
   at org.eclipse.e4.ui.internal.workbench.SelectionAggregator.notifyListeners(SelectionAggregator.java:109)
   at org.eclipse.e4.ui.internal.workbench.SelectionAggregator.access$4(SelectionAggregator.java:106)
   at org.eclipse.e4.ui.internal.workbench.SelectionAggregator$4$1.run(SelectionAggregator.java:163)
   at org.eclipse.e4.core.contexts.RunAndTrack.runExternalCode(RunAndTrack.java:53)
   at org.eclipse.e4.ui.internal.workbench.SelectionAggregator$4.changed(SelectionAggregator.java:161)
   at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.update(TrackableComputationExt.java:110)
   at org.eclipse.e4.core.internal.contexts.EclipseContext.processScheduled(EclipseContext.java:318)
   at org.eclipse.e4.core.internal.contexts.EclipseContext.set(EclipseContext.java:332)
   at org.eclipse.e4.ui.internal.workbench.SelectionServiceImpl.setSelection(SelectionServiceImpl.java:30)
   at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.selectionChanged(CompatibilityPart.java:420)
   at org.eclipse.gef.ui.parts.AbstractEditPartViewer.fireSelectionChanged(AbstractEditPartViewer.java:247)
   at org.eclipse.gef.ui.parts.AbstractEditPartViewer$1.run(AbstractEditPartViewer.java:131)
   at org.eclipse.gef.SelectionManager.fireSelectionChanged(SelectionManager.java:144)
   at org.eclipse.gef.SelectionManager.setSelection(SelectionManager.java:279)
   at org.eclipse.gef.ui.parts.AbstractEditPartViewer.setSelection(AbstractEditPartViewer.java:751)
   at org.eclipse.graphiti.ui.internal.editor.GraphitiScrollingGraphicalViewer.setSelection(GraphitiScrollingGraphicalViewer.java:64)
   at org.eclipse.graphiti.ui.internal.editor.GFMarqueeSelectionTool.performMarqueeSelect(GFMarqueeSelectionTool.java:526)
   at org.eclipse.graphiti.ui.internal.editor.GFMarqueeSelectionTool.handleButtonUp(GFMarqueeSelectionTool.java:392)
   at org.eclipse.gef.tools.AbstractTool.mouseUp(AbstractTool.java:1200)
   at org.eclipse.gef.tools.SelectionTool.mouseUp(SelectionTool.java:574)
   at org.eclipse.gef.EditDomain.mouseUp(EditDomain.java:301)
   at org.eclipse.gef.ui.parts.DomainEventDispatcher.dispatchMouseReleased(DomainEventDispatcher.java:380)
   at org.eclipse.draw2d.LightweightSystem$EventHandler.mouseUp(LightweightSystem.java:548)
   at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:220)
   at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
   at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
   at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4169)
   at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3758)
   at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1029)
   at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
   at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:923)
   at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
   at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)
   at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
   at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
   at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
   at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
   at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
   at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
   at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
   at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
   at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
   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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
   at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
   at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
   at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Session data:

eclipse.buildId=M20120914-1800
java.version=1.6.0_31
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=it_IT
Framework arguments:  -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product
‍‍‍‍‍‍‍‍

Eclipse was still started as Administrator.
Can you help me please?

Thanks a lot, regards

[hannibal80]

Fxxx! I got it!

I switched to "Package Explorer", I found the diagrams resources, I added a new diagram and now all it's working properly.

Sorry for my foolishness.