Well all works till i generate the signed apk . I followed the entire process as told on the google developers page
1.I generated the google-services.json file with
FWIW:
For me, I had the release and debug configuration (Oath client IDs, SHA-1, etc) all set up in the Google dev console and google-services.json file installed on the project.
Because I'm working with multiple build flavors, I put the various config files in their respective ./app/ directories.
My fault was failing to generate the signed APK with the correct keystore file, alias & password in the Generate Signed APK wizard. The wizard was caching keys and credentials from a previous build flavor (tsk). But after reseting the keys to map to the target flavor, I now have a working Google Sign in.