iOS app rejected - Gamekit / Game Center

Hello,

I just submitted a new app to the iTunes Store and it has been rejected for the following reason:

2.2

We found that your app exhibited one or more bugs, when reviewed on iPhone 5s running iOS 7.1.2, on both Wi-Fi and cellular networks, which is not in compliance with the App Store Review Guidelines.

When user launches the app, app requires Apple ID.

It indeed ask for an Apple ID because I use the Gamekit easy module which tries to connect to Game Center at startup.

I asked them what should I change but if someone had the same problem and could help, it would be great.

Thanks.