I would say you need to make

kazimmerman — Tue, 15 Dec 2009 17:04:41 +0000

I would say you need to make sure that for some reason GD is not disabled on your server. Otherwise, you might try using the imagepng() function instead and see if it makes any difference. If it does make a difference, support for JPEG output must not be available with your version of PHP/GD; otherwise, I would say it's a problem with the server itself as this seems to be an exact copy of the sample script available at the PHP.net website.