google cloud messaging - Android GCM not able to send notification to device -

google cloud messaging - Android GCM not able to send notification to device -

i followed illustration next website register device , subsequently send messages device.

http://androidexample.com/android_push_notifications_using_google_cloud_messaging_gcm/index.php?view=article_discription&aid=119&aaid=139

i both register , subsequently send notifications server device successfully.

however recently, stopped working. still register not send notifications.

any thought what's issue? did google changed recently?

android google-cloud-messaging