javascript menu on the back of the controls

[Das]

Hi all,
I'm using javascript menu in asp.net web control. My web from control menuControl & other controls like combo box & text box.
When I select the menu with the text box it comes in front of it. But menu goes on the back of the combo box. I don't know why it behaves like. Menu should come in front of the all controls. Is there any property that I need to set?

thanks
das