jQuery Mobile drop down in header

jQuery Mobile drop down in header

Hello, I want to put a drow-down menu in my jquery mobile webapp especially in the header.
My webapp: mobile.wks-webapp.bplaced.de

Login:
User: MockMode
Password: htlhl

I want to put the dop-down menu in the header of uebersicht.html and detail.html
My Problem is (uebersicht.html), when I open the drow-down menu I cannot open the Hilfe/Help PopUp.
In detail.html the drop-down isn't visible and I don't know why.