Problem with TreeTableView and IntelliJ 6

I'm creating a TreeTableView in my plugin. This works find under Intellij 5 but has some problems under Intellij 6, where it works in development, but not when downloaded as a plugin thru the plugin manager.

The error is:

Error during dispatching of java.awt.event.MouseEvent[MOUSE_RELEASED,(57,132),button=1,modifiers=Button1,clickCount=1] on ###overrideRedirect###: com.intellij.ui.dualView.TreeTableView.getTree()Lcom/intellij/util/ui/Tree;
java.lang.NoSuchMethodError: com.intellij.ui.dualView.TreeTableView.getTree()Lcom/intellij/util/ui/Tree;
at com.rk.jarjuggler.gui.TreeTablePanel.createDetailPanel(TreeTablePanel.java:78)

On line 78 I'm trying to attach a TreeSelectionListener to the JTree with this code:
treeTableView.getTree().addTreeSelectionListener(new TreeSelectionListener() {

I know the API slightly changed:
- in 5 getTree() returns a Tree
- in 6 getTree() returns a TreeTableTree

but both subclass JTree where addTreeSelectionListener() is.

Any ideas?

thanks
scott