i'm trying to set up imessaging on my ipod touch. When i get to the screen where i type in my user id and password, i hit the sign in button, the screen goes to the messaging screen and then flips back to the sign in screen and stops. i've tried this several times with the same result. my husband tried this using his login information and it worked fine. my apple id works fine on itunes but not with imessaging on my touch.