Xamarin.Auth with Google, Completed event doesn't fire?

I'm developing an application in pcl. I've implemented Facebook, Instagram login using Xamarin.Auth. In this case completed event fired, but in the case of Google after authentication, completed event doesn't fire. I've followed the procedure of Xamarin.Auth Google login with NativeUI and used Xamarin.Auth 1.5.0.3 Nuget version.