eclipse : adding JSF 2 facet results in NullpointerException

I have a maven project, and then, i would like to enable JSF 2 facet into the project, because i realized that i cant do the auto completion with the jsf / primefaces tags and with the tag attributes with the ctrl space when editing my jsf page.

Enabling the JSF 2 facet in my Helios eclipse results in NullPointerException, with this complete exception trace :

!ENTRY org.eclipse.wst.common.project.facet.core 4 0 2011-01-18 22:45:17.073 !MESSAGE null !STACK 0 java.lang.NullPointerException at org.eclipse.jst.jsf.core.internal.project.facet.JSFFacetInstallDataModelProvider.validateConfigLocation(JSFFacetInstallDataModelProvider.java:232) at org.eclipse.jst.jsf.core.internal.project.facet.JSFFacetInstallDataModelProvider.validate(JSFFacetInstallDataModelProvider.java:161) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelImpl.validate(DataModelImpl.java:377) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelImpl.validate(DataModelImpl.java:358) at org.eclipse.wst.common.componentcore.datamodel.FacetDataModelConfigAdapter.validate(FacetDataModelConfigAdapter.java:63) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage.updateFurtherConfigHyperlink(FacetsPropertyPage.java:422) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage.access$4(FacetsPropertyPage.java:337) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage$6.run(FacetsPropertyPage.java:330) at org.eclipse.wst.common.project.facet.ui.internal.util.SwtUtil.runOnDisplayThread(SwtUtil.java:34) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage.handleProjectModifiedEvent(FacetsPropertyPage.java:334) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage.access$2(FacetsPropertyPage.java:324) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage$3.handleEvent(FacetsPropertyPage.java:189) at org.eclipse.wst.common.project.facet.core.internal.FacetedProjectWorkingCopy.notifyListeners(FacetedProjectWorkingCopy.java:1752) at org.eclipse.wst.common.project.facet.core.internal.FacetedProjectWorkingCopy.resumeEventNotification(FacetedProjectWorkingCopy.java:1797) at org.eclipse.wst.common.project.facet.core.internal.FacetedProjectWorkingCopy.addProjectFacet(FacetedProjectWorkingCopy.java:822) at org.eclipse.wst.common.project.facet.ui.internal.FacetsSelectionPanel.handleCheckStateChanged(FacetsSelectionPanel.java:758) at org.eclipse.wst.common.project.facet.ui.internal.FacetsSelectionPanel.access$10(FacetsSelectionPanel.java:729) at org.eclipse.wst.common.project.facet.ui.internal.FacetsSelectionPanel$6.checkStateChanged(FacetsSelectionPanel.java:309) at org.eclipse.jface.viewers.CheckboxTreeViewer$1.run(CheckboxTreeViewer.java:166) 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.CheckboxTreeViewer.fireCheckStateChanged(CheckboxTreeViewer.java:164) at org.eclipse.jface.viewers.CheckboxTreeViewer.handleSelect(CheckboxTreeViewer.java:300) at org.eclipse.jface.viewers.StructuredViewer$4.widgetSelected(StructuredViewer.java:1220) at org.eclipse.jface.util.OpenStrategy.fireSelectionEvent(OpenStrategy.java:228) at org.eclipse.jface.util.OpenStrategy.access$4(OpenStrategy.java:222) at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:389) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3540) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3161) at org.eclipse.jface.window.Window.runEventLoop(Window.java:825) at org.eclipse.jface.window.Window.open(Window.java:801) at org.eclipse.ui.dialogs.PropertyDialogAction.run(PropertyDialogAction.java:157) at org.eclipse.jface.action.Action.runWithEvent(Action.java:498) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584) at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501) at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3540) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3161) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438) at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115) 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:369) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574) at org.eclipse.equinox.launcher.Main.run(Main.java:1407) !ENTRY org.eclipse.wst.common.project.facet.core 4 0 2011-01-18 22:45:18.622 !MESSAGE Failed while installing JavaServer Faces 2.0. !STACK 0 java.lang.NullPointerException at org.eclipse.jst.jsf.core.internal.project.facet.JSFFacetInstallDelegate.resolveConfigPath(JSFFacetInstallDelegate.java:296) at org.eclipse.jst.jsf.core.internal.project.facet.JSFFacetInstallDelegate.createConfigFile(JSFFacetInstallDelegate.java:313) at org.eclipse.jst.jsf.core.internal.project.facet.JSFFacetInstallDelegate.execute(JSFFacetInstallDelegate.java:124) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject.callDelegate(FacetedProject.java:1478) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject.modifyInternal(FacetedProject.java:442) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject.mergeChangesInternal(FacetedProject.java:1182) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject.access$2(FacetedProject.java:1118) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject$5.run(FacetedProject.java:1100) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975) at org.eclipse.wst.common.project.facet.core.internal.FacetedProject.mergeChanges(FacetedProject.java:1110) at org.eclipse.wst.common.project.facet.core.internal.FacetedProjectWorkingCopy.commitChanges(FacetedProjectWorkingCopy.java:2020) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage$4.run(FacetsPropertyPage.java:232) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975) at org.eclipse.wst.common.project.facet.ui.internal.FacetsPropertyPage$5.run(FacetsPropertyPage.java:246) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121) 

What could be wrong here .. or ..

Perhaps there is some other ways to enable the auto completion without adding the dynamic web module and jsf 2 facets in the Eclipse Helios ?