Transparency Menu Backgrounds?

Could anyone please tell me if UIS2 skins can have transparency in any of the menu background images? For example my More Programs Menu Backgound image shows magic pink if I try to use a bmp file and add a Trans=1 line in the code, or black where I try to use a tga file when there is a Trans=1 line and a PerPixel=1 line in the code.
If this is just not supported then please someone put me out of my misery so I can stop battling with this! >

Thanks in advance!