Push notification using GCM with Asp.net server

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http://stackoverflow.com – If my device is offline or switched off at the time server is sending the push message, then when it is getting online(active) it should receive all pending notifications. It is not receiving the push notification of my app. What might be the reason???? Please help me to solve this issue. String I am posting from server side(Asp.net server) to GCM server: String postdata= "collapse_key=score_update"+i+"&time_to_live=2419200&delay_while_idle=1&data.message=‌​"+ message + "&data.time=" + System.DateTime.Now.ToString() + "&registration_id=" + deviceTo (HowTos)