How to show hidden div on top of other divs positioned absolute?

[99_Roy]

I'm working with MVC3 to create a simple website. But the thing is with CSS. I have created a header page, and added my menu to it (I want the menu to be displayed on all pages). For submenus, I have created hidden divs for each menu item, which are displayed when menu-items are hovered over and disappears when hovered out. Everything is fine for other pages but on one of the pages, I was creating slide effect using fadeIn() fadeOut() of 3 images contained in a single div, positioned absolute(so that they lie over each other). But now the hidden divs don't come above(z-index towards user) but comes below the images and thus cannot be seen completely. I have tried altering z-indexes of hidden divs and images but that didn't help. How to bring the hidden divs on top??