IE8 opacity animate on a png transparent

IE8 opacity animate on a png transparent

I try to animate the opacity of a div which have a .png background.
<div id="image" style="background:url('background.css') repeat-x";></div>
For that, I use this code :
$("#image").stop().animate({
opacity: 1
}, 1000, "easeInOutSine", function() {
$("#image").stop().animate({
opacity: 0
}, 1000, "easeInOutSine");
});
It's ok for recent browsers. But in IE 7 and 8, the transparence is
black... I looked for a solution but none works. Someone can help me?
Thanks