Alt Key and Menu-Toolbar

I've a dialog based application and use a CXTPMenuBar. Its working fine except two issues:

1) the ALT key does not activate the menu like usually, I use the following code to create the MenuBar

 m_wndMenuBar.CreateToolBar(WS_CHILD|WS_VISIBLE|CBRS_GR IPPER, this);
  m_wndMenuBar.LoadMenuBar(IDR_MENU_MAIN);
 m_wndMenuBar.SetFlags(xtpFlagStretched | xtpFlagHideWrap | xtpFlagAlignAny);

2) I'am not able to reload the Menubar with m_wndMenuBar.LoadMenuBar(IDR_MENU_MAIN);

The problem here, I like to switch the language and for this reason I derived CTPMenuBar and overloaded the LoadMenuBar method. It doesn't work, because the I think the MenuBar is not empty on the second call!?!

Thanks a lot for your help