[gtkmm] Problem with libglademm with Popup context menu

["PenguinMan" <linux cwazy co uk>]

Look at this code:

....
Gtk::TreeView* m_TreeView;
....

....
m_refGlade->get_widget( "treeview1", m_TreeView );
....

Everything works well.
But I want to use Gtk::TreeView with popup context menu. So here is my code:

....
TreeView_WithPopup* m_TreeView;
....

....
m_refGlade->get_widget( "treeview1", m_TreeView );
....

m_TreeView did not show up and I got this message:
** (treeview:13548): CRITICAL **: Gnome::Glade::Xml::get_widget():
dynamic_cast<> failed.

How do I solve my problem here?
Thank you.

gtkmm-2.4, libglademm-2.4.