CSS background image does not show up in IE 7 and 8

URL i开发者_运维知识库s http://site1.ewart.library.ubc.ca/node/255

The carousel on the page has a background image

#webcastingslideshow {
    background: url("images/webcasting/carousel_background.png") no-repeat scroll left   top transparent;
}

It works on FF (and Chrome) but not with IE 7 and 8. Instead, the background image does not show up in IE at all (just a white background).

I guess it might be some overlay of DIVs but I am not sure.

Any advice?

Thank you,

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Add overflow: hidden to #webcastingslideshow.