roll over effect, show another image

[fadiodeh]

I have an href image in this markup. \[code\]<div class="imgdiv"> <a class="imga" href="http://destination.com"> <img src="http://image.com/image.jpg" width="100" height="100"> </a></div>\[/code\]When I hover over it, I want to show another image in the top right corner. Is this doable with css? or do I need javascript for that?My CSS looks like this but it still doesn't work\[code\]a.imga:hover { background-image: url('over.png'); background-position: top; z-index:3;}\[/code\]