pop up menu going under combo box...How to bring it up?

Hi ! i created a pop up menu using javascript... and placed a combo box below it.when the menu is droped, it is going below the combo box(not only combo box,it is happening with all other form elements).not able to see the pop up below it.How to bring the menu up the combo box.
NOTE :- it is working properly in mozilla fierfox browser. but when i am using Internet explorer...

Hi,

In one of my webpage, i have used iframe in which i have placed combobox, textfeilds etc.. above this iframe there is a pop up menu. when mouse overs the menu is droped under the form elements. I want the menu to be displayed over the form elements. problem is that when i use firefox for the display, there it is fine. but when i am using IE for display, i am facing this problem.

please reply me with the appropriate...