Android Notification小图标在

Question

在推送通知中，小图标不会显示在OS.White square上面的7.1.1中，如

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context);
Notification notification = mBuilder.
        setSmallIcon(R.drawable.notification_icon).
        setTicker("testing").setWhen(0)
        .setAutoCancel(true)
        .setContentTitle(title)
        .setContentIntent(contentIntent)
        .setSound(defaultSoundUri)
        .setContentText(message)
        .build();

notification.flags = Notification.FLAG_AUTO_CANCEL;
notificationManager.notify(NOTIFICATION_ID, notification);

我使用透明背景，但我无法正确显示请帮助我。即使我遵循Android图标设计指南。