jdeveloper database connection problem

[Mustafa Turan]

we have oracle 9i database and jdeveloper 10g installed on our
machine. we tried to connect our database in jdeveloper by using new
database connection wizard. at the end of the connection wizard, tool
says that the connection is successful(by issuing the message
"Success!"). At the end we get the following exception:
java.lang.NullPointerException
at oracle.jdevimpl.cm.dt.ConnectionController$ConnectionExpander.selectConnection(ConnectionController.java:547)
at oracle.jdevimpl.cm.dt.ConnectionController$ConnectionExpander.access$1000071(ConnectionController.java:514)
at oracle.jdevimpl.cm.dt.ConnectionController.runNewConnectionDialog(ConnectionController.java:508)
at oracle.jdevimpl.cm.dt.ConnectionController.runNewConnectionDialog(ConnectionController.java:484)
at oracle.jdevimpl.cm.dt.NewConnectionWizard.invoke(NewConnectionWizard.java:71)
at oracle.ide.WizardManager.invokeWizard(WizardManager.java:484)
at oracle.ide.WizardManager$1.run(WizardManager.java:538)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:454)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

how can we solve the problem?
thanks in advance.