Hi there. It's me again, under another name, and I'd like to know about something I've been having trouble with lately on the forums.

On my signature, I'm trying to display a 500x100 pixel GIF that includes transparent background and a mesh between a Jazz screenshot and a nifty fire-text image of my name.

However, when I try to post it, I get the following message.

It's nice to let me know and all, but could someone give me the details on what's wrong with my image?