GCM:一些设备在android中没有收到推送通知

我正在从php服务器向android设备发送推送通知，但有些设备没有收到推送通知。

这是来自服务器的状态

{"multicast_id":4893937277293136804,"success":4,"failure":10,"canonical_ids":0,"results":[{"error":"NotRegistered"},{"error":"NotRegistered"},{"error":"NotRegistered"},{"error":"NotRegistered"},{"message_id":"0:1452592669440333%c40440a4f9fd7ecd"},{"error":"NotRegistered"},{"error":"NotRegistered"},{"message_id":"0:1452592669442897%c40440a4f9fd7ecd"},{"error":"NotRegistered"},{"error":"NotRegistered"},{"message_id":"0:1452592669442899%c40440a4f9fd7ecd"},{"error":"NotRegistered"},{"error":"NotRegistered"},{"message_id":"0:1452592669442901%c40440a4f9fd7ecd"}]}

PHP

$key="XXXXXX";
  $url = 'https://android.googleapis.com/gcm/send';
  $fields = array(
                'registration_ids'  =>$result,
                'data'              => array( "message" =>$msg,"title"=>$title,"soundname"=>"beep.wav" ),
                );
  $headers = array(
                    'Authorization: key=' . $key,
                    'Content-Type: application/json'
                );
 try{
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
  curl_setopt( $ch, CURLOPT_URL, $url );
  curl_setopt( $ch, CURLOPT_POST, true );
  curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers);
  curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
  curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $fields ) );
  $res = curl_exec($ch);
  print_r($res)
  }

从响应中，只有4台设备成功获得响应，但发生了10次故障。

问题出在哪里？