[Aerogear-users] GCM Registration Not happening

Hi, I have followed following link for Android app with AeroGear https://aerogear.org/docs/unifiedpush/aerogear-push-android/guides/ I am not able to receive GCM notification. When trying to send gcm notification getting following response :- { "multicast_id": 9021705393385917000, "success": 0, "failure": 1, "canonical_ids": 0, "results": [ { "error": "NotRegistered" } ] } What can be possible reason for this?