From: Birdsboro, PA, USA
Couple things it could be, see if he can tell you the time/date stamp of the file he got from you, see if it is indeed the one you sent him, sometimes if one is not carteful, and log everything, it can get confusing!!
Also, occasionally, if you exit the game too fast after hitting next turn, it can be corrupted.
Make sure also, that he or you actually pressed the next turn button, happens!!
Hope this helps?!
Meine Ehre heißt Treue