Popup Menu doesn't work with IE

Hello
I have a button on my mainform.
On action i do:

// TODO Auto-generated method stub
	var popupmenu = plugins.window.createPopupMenu()
	var _element = event.getElementName();
	
	if (_element == "Stammdaten") 
	{
		var smenuitem1 = popupmenu.addMenuItem('Pflege User',globals.m_gotoForm);
				
		var ssubmenu1 = popupmenu.addMenu('Arbeitsgruppen/Prüfungskommissionen');
		var ssubitem11 = ssubmenu1.addMenuItem('Pflege Arbeitsgruppen',globals.m_gotoForm);
		var ssubitem12 = ssubmenu1.addMenuItem('Pflege Prüfungskommissionen',globals.m_gotoForm);
		
		var ssubmenu2 = popupmenu.addMenu('Basistabellen');
		var ssubitem21 = ssubmenu2.addMenuItem('Pflege_Länder',globals.m_gotoForm);
		var ssubitem22 = ssubmenu2.addMenuItem('Pflege Zertifizierungsverfahren',globals.m_gotoForm);
		var ssubitem23 = ssubmenu2.addMenuItem('Pflege Kompetenzgruppen',globals.m_gotoForm);
		
		
	}

In Version 5 this worked with IE and Firefox.

After upgrading to 6.01 with firefox everything is still OK.
With IE only the first level is shown??? (Pflege User, Arbeitsgruppen/Prüfungskommisionen,Basistabellen)
The second level is not shown (Pflege Länder,Pflege Zertifizierungsverfahren,…)

I use IE7. My customers reported the same problem, but i don’t know which version of IE they use.

Need help
Regards
Albert

please make a case with a small example