[jQuery] Fade-in problem in IE7(urgent)

[Rupak]

Hi all

Please help me out. I am using fadeIn in a transparent(background)
div. I works fine in FF but transparency will disappear in IE.

first test in FF and then in IE, and see the difference.
http://jsbin.com/icatu

css & js code

<style type="text/css" media="screen">
.div1
{
  background-color:#000000;
  width:200px;
  height:200px;
  filter:alpha(opacity=50);
  opacity:.5;
  display:none;
 }
</style>
<script>
$(document).ready(function(){
$(".div1").fadeIn(5000);
})
</script>


Thanks
Rupak