Unusual eclipse plug-in problem - eclipse

Question

I have this very unusual problem.
I developed this plugin with property page. When I run plug-in as Eclipse application it works perfectly, but when I export it and copy it to eclipse/dropin folder I get ClassNotFoundException.
My Manifest.mf looks like this:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: SpectrumPlugin
Bundle-SymbolicName: sinaut.spectrum.plugin; singleton:=true
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: sinaut.spectrum.plugin.activator.SpectrumPluginActivator
Require-Bundle: org.eclipse.core.runtime;bundle-version="3.4.0",
org.eclipse.ui;bundle-version="3.4.2",
org.eclipse.core.resources;bundle-version="3.4.2",
org.eclipse.ui.console;bundle-version="3.3.1"
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Bundle-ClassPath: JARs/sshfactory.jar,
.
Import-Package: org.eclipse.ui.console
Export-Package: com.jscape.a,
sinaut.spectrum.plugin.activator,
sinaut.spectrum.plugin.ftp,
sinaut.spectrum.plugin.preferences,
sinaut.spectrum.plugin.remotebuild,
sinaut.spectrum.plugin.ssh
plugin.xml looks like this:
<plugin>
<extension
point="org.eclipse.ui.preferencePages">
<page
id="BildPreferencePage"
name="Bild Preferences"
class="sinaut.spectrum.plugin.preferences.BildPreferencePage"
>
</page>
</extension>
<extension
point="org.eclipse.core.runtime.preferences">
<initializer
class="sinaut.spectrum.plugin.preferences.PreferenceInitializer">
</initializer>
</extension>
<extension
point="org.eclipse.ui.actionSets">
<actionSet
id="sinaut.spectrum.plugin.RemoteBildActionSet"
label="RemoteBildActionSet"
visible="true">
<menu
id="sinaut.spectrum.plugin.RemoteBuildMenu"
label="Remote Build Menu">
<groupMarker
name="content">
</groupMarker>
<separator
name="additions">
</separator>
</menu>
<action
class="sinaut.spectrum.plugin.remotebuild.RemoteBuild"
icon="/icons/rb.gif"
id="sinaut.spectrum.plugin.RemoteBuild"
label="Remote Build"
state="true"
style="push"
toolbarPath="Normal/additions">
</action>
</actionSet>
</extension>
</plugin>
And I've got this message when I try to start this property page "Unable to create the selected preference page.sinaut.spectrum.plugin.preferences.BildPreferencePage", with this stack trace:
java.lang.ClassNotFoundException: sinaut.spectrum.plugin.preferences.BildPreferencePage
at org.eclipse.osgi.framework.internal.core.BundleLoader.findClassInternal(BundleLoader.java:483)
at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:399)
at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:387)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:87)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:315)
at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:227)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1274)
at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:160)
at org.eclipse.core.internal.registry.ExtensionRegistry.createExecutableExtension(ExtensionRegistry.java:867)
at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:243)
at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:51)
at org.eclipse.ui.internal.WorkbenchPlugin$1.run(WorkbenchPlugin.java:267)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:263)
at org.eclipse.ui.internal.dialogs.WorkbenchPreferenceNode.createPage(WorkbenchPreferenceNode.java:47)
at org.eclipse.jface.preference.PreferenceDialog.createPage(PreferenceDialog.java:1306)
at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.createPage(FilteredPreferenceDialog.java:385)
at org.eclipse.jface.preference.PreferenceDialog.showPage(PreferenceDialog.java:1197)
at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.showPage(FilteredPreferenceDialog.java:682)
at org.eclipse.jface.preference.PreferenceDialog$10.run(PreferenceDialog.java:702)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.jface.preference.PreferenceDialog$9.selectionChanged(PreferenceDialog.java:698)
at org.eclipse.jface.viewers.StructuredViewer$3.run(StructuredViewer.java:842)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
at org.eclipse.core.runtime.Platform.run(Platform.java:880)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
at org.eclipse.jface.viewers.StructuredViewer.firePostSelectionChanged(StructuredViewer.java:840)
at org.eclipse.jface.viewers.StructuredViewer.handlePostSelect(StructuredViewer.java:1153)
at org.eclipse.jface.viewers.StructuredViewer$5.widgetSelected(StructuredViewer.java:1178)
at org.eclipse.jface.util.OpenStrategy.firePostSelectionEvent(OpenStrategy.java:250)
at org.eclipse.jface.util.OpenStrategy.access$4(OpenStrategy.java:244)
at org.eclipse.jface.util.OpenStrategy$3.run(OpenStrategy.java:418)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:133)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3378)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3036)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:825)
at org.eclipse.jface.window.Window.open(Window.java:801)
at org.eclipse.ui.internal.OpenPreferencesAction.run(OpenPreferencesAction.java:65)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:583)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:500)
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:1158)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3401)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3033)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2384)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2348)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2200)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:495)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:490)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)
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:386)
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:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
at org.eclipse.equinox.launcher.Main.run(Main.java:1236)
It must be something stupid, but I just can't see it.
If anyone can help me with this. I've been stuck for hours on this.

Answer 1

Launch eclipse with below argument
-console
Then find your plug-in id in OSGi console like
ss sinaut.spectrum.plugin
Last using diag to see why your plug-in can't be resolved
diag <id found by ss command>
and try to start it to see whether anything is wrong in its activator
start <id>