Goodgle Play Services Crashing App

C. Victory

I need some help with Google Play services. Everything works perfectly on iOS, but game crashes whenever it tries to post achievement or scores to google play services. So if you login to google play services at any time and then tries to post achievement or scores, the game crashes. But if you do not login to play services, it works perfectly, but would not post scores/acheivements. I am not sure how to resolve this. Thanks in advance.