transparent images

i tried to make one color of my image (in a picturebox) transparent. But the only thing I manage to do is making one color the same color as my form. For this I used some code i found in the msdn-libraries:

Dim g As New System.Drawing.Bitmap(Button1.BackGroundImage)
g.MakeTransparent(System.Drawing.Color.White)
Button1.BackgroundImage = g

I adjusted the code so it would be useful to an image in a picturebox but it isn't realy transparent, it gets the collor of the form it's on

in VB6 I could just use a transparent GIF-image, in VB.net this doesn't work anymore.

Is there someone who could help me?

most of us do not know .NET here. you would be better off posting your question here:

http://vbforums.com/forumdisplay.php?s=&forumid=25