Cannot login to FaceTime

I'm having problems logging into FaceTime. Have been using it ok since we got my daughters iPad2 at Christmas but all of a sudden cannot login.

I enter the apple ID which is my email address and then my password, it goes to the next screen, where I hit next but it keeps on reverting to the original screen.

I have tried this on two separate accounts and also created a new account for my wife but cannot login on any of them.

I have tried resetting but this does not fix the problem. Any ideas?