I can't login to game center.
I just got a new iPhone 6, and was transferring things over to it, and one thing I was concerned with was game center. I wanted to transfer over a game to my new iPhone and I can't log in to game center. I have remade my password twice now because I thought that I originally forgot it, but now that I've reset it twice and am positive I'm submitting the correct password, I'm confused. Please help.
iPhone 6, iOS 8.3