IE7 Layer transpanecy

Does any one know why layer transparency stopped working in IE7, and or when it might be fix/pached. I had been using the function below to set transparencies for IE 5.5, IE6.0, Gecko based browsers, and Oprea.

But since IE7 it has stopped working. I have not found any thing on MSDN about the IE DOM not supporting the alpha/opacity atribute any more. Does any one have any details about this

function setTransparency(layerItem, opacityValue) {
//
// Validate layer object
//
if ( layerItem == null ) { return; }
if ( layerItem.style == null ) { return; }
//
// Set transparency for the IE DOM
//
pageItem.style.filter = "alpha(opacity="+opacityValue+")";
//
// Set transparency for the W3C DOM
//
pageItem.style.opacity = (opacityValue /100);
}