Where did you get your AIM program from? There are several out there and I had to find the right one for mobile that would take my info.
Alternatively...you might look in Palringo. It offers support for Yahoo, Gmail, AIM, etc....all in one neat package.
Look here to find out more:
http://www.ppcgeeks.com/palringo-ptt...-07-t4525.html
late,
Coz