imagelist control

hi, i'm using the imagelist control and i have a problem with the maskcolor property. isn't it supposed to make the selected color transparent? i'm trying to overlay two images (jpg) which both have red backgrounds, so I set the maskcolor to red:

ImageList1.MaskColor = vbRed

and then i overlay them and paste them on a picturebox.

Set Picture1.Picture = ImageList1.Overlay(1,2)

The problem is that I can still see the red, it isn't becoming transparent... am I doing anything wrong??
I've also tried to change de maskcolor property directly in the imagelist properties dialog, but i doesn't work either.
Thank you!

I can't find documentation to support it, but I suspect that the Overlay method doesn't work with JPGs. I would suspect that it only works with MS image types like BMPs and ICOs. JPG format is more complex and as far as I know JPG usually isn't associated with transparency operations (the way GIFs are for the web or BMPs are for Windows).

Good luck,
Paul