How to use GuiFileTreeCtrl in T3D?

I placed a GuiFileTreeCtrl into mainmenu.
but it shows nothing.

then i have set the rootpath to "art".
same result.
no error or warning!

after debugging i found out inside GuiFileTreeCtrl::onWake() it always return false.

sourceguicontrolsguiFileTreeCtrl.cpp

bool GuiFileTreeCtrl::onWake()
{
   if( !Parent::onWake() )
      return false;------------>always returned from here
      
   updateTree();-----------never called

   return true;
}

anyidea why it returned back?

old link:
same problem with some error notification.unsolved.
http://www.garagegames.com/community/forums/viewthread/131367/1#comment-847490