We are having the same issue. We have looked at the div and iframe, and are curious if there's been any issue with permissions that prevent the bg image from appearing.
We've processed pixels, have a current version of PHP, and GD library is fine. We've gone over several png versions with alpha channel modifications.... Test blocks are visible, but background is not. PLEASE HELP -- LAUNCH TOMORROW!
Could you provide a sample PNG background that is known to work. There is one that you have linked at
www.milliondollarscript.com/admin/temp/background.png but it yields a 404 error.