Coolbar and Background Image

I posted this in VCL Components but had no replies.

I just converted from Delphi 3 to 4. A form I have with a cool bar has a
background image. Under Delphi 3 the buttons on the coolbar showed the
marble image as part of the the buttons, a transparent look. In Delphi 4 the
image does not show through. It just looks like square buttons on top of the
background
image. I checked all of the properties but couldn't see anything that has
changed since Delphi 3.

Any ideas on why the image does not show through properly in Delphi 4?

Thanks

Wayne