why GCM is not giving push notification in android device?

Question

I am new to android and doing a demo app for gcm push notification.

I have developed all this code and GCM push notification is coming on devices in my environment, but

Answer 1

At last I found the reason.My company firewall was blocking all messages from GCM. So I just removed firewall and able to receive messages from GCM . Go through this link to know more about firewall issues

Hope it will help somebody in future.