Opacity lost on background image

[createErrorMsg]

I'm trying to use a PNG image with a transparent background and an opaque foreground for a rollover button. Firefox (big fanfare!) works like a dream, giving me ghostly button boxes just like I wanted, but IE, clunker that it is, turns the buttons solid.

Anyone know how to get an opaque image to stay opaque in IE?

PS: I posted this two days ago on the graphics forum and got no response. Since I'm using the image for css rollover buttons, I figured I'd try my luck with the smart people ;)

[drbrain]

IE only supports PNG transparency via a special filter CSS property whose invocation I forget.

[SuzyUK]

The filter is included in Dean Edwards IE7 [dean.edwards.name] suite and if you search for "png transparency behaviour file" there is also another site which explains the png filter and provides a behaviour file on just this filter alone.

Suzy