My iMessages will not activate, please help.

On my ipad 2, when i try to log into imessages with my account, it keeps bouncing me back before i have a chance to hit next on choosing the e-mail id. I get back to the sign in page and i don't understand what the problem is, it worked on my friend's ipad 2. This happened right after updating to iOS 5 today. I even changed my pw to see if that would fix the issue. I restarted the ipad, but nothing 😟 please help.