android很小的问题为什么notification设置了setTicker也不会在通知栏出现？

 package com.example.notificationtest;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);
        Button sendNotice = (Button) findViewById(R.id.send_notice);
        sendNotice.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
                PendingIntent pendindIntent = PendingIntent.getActivity(
                        MainActivity.this, 0, new Intent(MainActivity.this,
                                Notification.class), PendingIntent.FLAG_CANCEL_CURRENT);
                Notification notification = new Notification.Builder(
                        MainActivity.this).setSmallIcon(R.drawable.ic_launcher)
                        .setTicker("it's  ticker text" )
                        .setContentTitle("content title")
                        .setContentText("content text")
                        .setContentIntent(pendindIntent).build();
                notification.flags |= Notification.FLAG_AUTO_CANCEL;
                manager.notify(1, notification);
            }
        });
    }
}

为什么我的notification设置了setTicker("it's ticker text" )也不会在status bar出现？？

http://www.myexception.cn/android/1654945.html