problems in game center

Hello trankiemhung,

Thanks for using Apple Support Communities.

I found the following information that will help resolve your issue:

Using Game Center

http://support.apple.com/kb/HT4314

Additional Information

If you are having difficulty logging in to Game Center or staying connected

1. Verify that you are connected to the Internet.
2. If you are unable to create or sign in to your Game Center account from within a game, try creating or signing in to your account using the Game Center app.
3. Try signing out of your Game Center account, then sign back in. If you can't sign in to your Game Center account with an Apple ID, try resetting your password or using another email address. To manage your Apple ID account, go to My Apple ID.
4. When using a Wi-Fi connection, verify that your Wi-Fi router is configured for Game Center.

Take care,

Alex H.