How do you overlap an element over another element that is positioned relatively in Internet Explorer? Z-index doesn't work, it always appears behind the relatively positioned element.
Known issue, well-documented fix:
http://www.brenelz.com/blog/2009/02/03/squish-the-internet-explorer-z-index-bug/
Internet Explorer and z-index is a HUGE pain. It does work.
Run a google search for "IE z-index bug" and you'll be able to find help that will relate to your markup
EDIT: If you're going to mark my answer down, please explain why. If I'm wrong I'd also like to know why
You're not by any chance trying to put something over a combobox (select tag), iframe or flash movie right?
In those cases z-index is a lost cause.
Otherwise what browser version are you using and are you using absolute positioning?
I had a real pain with this problem that this particular workaround wasn't relevant for. It's a little hard to explain so I'll try using code:
<div id="first" style="z-index: 2">In between</div>
<div id="second" style="z-index: 1">In the back
<div id="third" style="z-index: 3">Foreground</div></div>
The problem is that setting the parent's z-index to a higher value would move it to the foreground instead of the back where its supposed to be. I stumbled upon a solution completely by accident: I made a copy of the foreground element (id=third) outside its parent.
<div id="first" style="z-index: 2">In between</div>
<div id="third" style="z-index: 3; visibility:hidden">Foreground</div>
<div id="second" style="z-index: 1">In the back
<div id="third" style="z-index: 3">Foreground</div></div>
Its worth mentioning that in my original code the elements don't have IDs so I don't suffer from 2 elements sharing the same one and invalidating my HTML.
I think its safe to classify this weirdness as another bug that happens to help with the original, but it works, at least for me. Hope somebody finds this useful!