Android中针对同一应用程序的多个通知无法正常工作？

我已经为我的android应用实现了推送通知。我能够在通知栏中显示多个通知，但一次只能显示一个通知。如果我单击任何通知，它将启动预期的活动，并且该特定通知将从通知栏中消失但是同一个应用程序的其他通知将失效。单击其余通知时什么也没有发生。我处理通知的代码如下：

private void sendNotification(String msg, String msgId, int notificationId,
            int type) {
        // SharedPreferences prefs = getSharedPreferences(
        // Utility.PREFS_NAME, MODE_PRIVATE);
        mNotificationManager = (NotificationManager) this
                .getSystemService(Context.NOTIFICATION_SERVICE);

        Intent intent = null;
        Bundle bundle = new Bundle();
        if (type == 1) {
            intent = new Intent(this, Activity_Received.class);

            // bundle.putString("greeting", msg);
            bundle.putString(Utility.KEY_MESSAGE_DELIVERY_ID, msgId);

        } else if (type == 2) {
            intent = new Intent(this, Activity_Birth.class);

        } else {
            return;
        }

        bundle.putBoolean(Utility.KEY_IS_NOTIFICATION, true);
        intent.putExtras(bundle);

        PendingIntent contentIntent;

        // 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.
        TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
        // Adds the back stack for the Intent (but not the Intent itself)

        if (type == 1) {
            stackBuilder.addParentStack(Activity_Received.class);
        } else {
            stackBuilder.addParentStack(Activity_Birth.class);
        }
        // Adds the Intent that starts the Activity to the top of the stack
        stackBuilder.addNextIntent(intent);

        contentIntent = stackBuilder
                .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT
                        | PendingIntent.FLAG_ONE_SHOT);

        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
                this)
                .setSmallIcon(R.drawable.ic_launcher)
                .setContentTitle("WishnGreet")
                .setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
                .setContentText(msg)
                .setAutoCancel(true)
                .setSound(
                        RingtoneManager
                                .getDefaultUri(RingtoneManager.TYPE_NOTIFICATION));


        mBuilder.setContentIntent(contentIntent);
        mNotificationManager.notify(notificationId, mBuilder.build());
    }

请告知我需要在上述代码中进行哪些更改，以便可以单击收到的有关我的应用程序的所有通知并开始预期的活动。