If you're hosting it on TPM, file size can be an issue (although I don't know what the limit is). I'd try hosting it on another site (like the link you provided, for instance) and just assigning your avatar to that address.
(I'm assuming you're trying to host it on TPM, because the image information shows a TPM address, not one of another site. If that's not the problem, then... uh, good luck?)
To assign your avatar to a web address for another site:
1. Go to your profile.
2. Instead of browsing your computer to upload the image, use the area just above it to specify the picture's URL.
3. Admire your spiffy new avatar.