通知无效

Question

尝试发送通知，但以下操作无效：

NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(this)
                        .setSmallIcon(R.drawable.icon_logo)
                        .setContentTitle("My notification")
                        .setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
        Intent resultIntent = new Intent(this, MainActivity.class);

// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
        android.support.v4.app.TaskStackBuilder stackBuilder = android.support.v4.app.TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
        stackBuilder.addParentStack(MainActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
        stackBuilder.addNextIntent(resultIntent);
        PendingIntent resultPendingIntent =
                stackBuilder.getPendingIntent(
                        0,
                        PendingIntent.FLAG_UPDATE_CURRENT
                );
        mBuilder.setContentIntent(resultPendingIntent);
        NotificationManager mNotificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// mId allows you to update the notification later on.
        mNotificationManager.notify(1, mBuilder.build());
        Log.i("GCM", "Got here"); 

它能够“到达这里”，但无法向我的手机发送通知。这是因为我需要特定的许可，还是我做了非法的事情？

请指教。

谢谢！