Wow it might be because it has Japanese text in it...
Other then that i don't know.
I don't think you had to be here a year, although I may be mistaken. I don't see anythinng on the FAQ, but on the page it is very vague and just says "New members may be unable to upload an avatar," Well that is the only possible reason I see. I'd ask in the Team Compendium Hidout forum where only the admins will be able to read it.