Error message when battling friends

I am trying to battle a friend of mine over WIFI. When we connect to each other we get an error message that says, " Invite Rejected Message Key". Has anyone else gotten this? Any advice how to fix this??

I had that too. 

The fix for me was 

  1. sign out of gamecenter

  2. restart the device

  3. sign back in gamecenter and see if it works

That fixed it for me. anyways whatever you do.  DO NOT UN INSTALL THE GAME. if you do so your save file will be deleted.

This was great advice.  It worked after doing what you suggested. Thanks!!