Unity - A计划（永久有效期） 扫二维码继续学习 二维码时效为半小时

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using GoogleMobileAds.Api;

public class GoogleAdManager : MonoBehaviour
{
    public string adUnitId = "";
    private BannerView bannerView;
    // Use this for initialization
    void Start () {
        this.RequestBanner();
    }

    private void RequestBanner()
    {
        bannerView = new BannerView(adUnitId, AdSize.Banner, AdPosition.Bottom);
        AdRequest request = new AdRequest.Builder().Build();
        bannerView.LoadAd(request);
    }
    void Update () {
        
    }

    void OnDestroy()
    {
        bannerView.Destroy();
    }
}

上面是代码了，运行游戏后的提示。导出apk后在模拟器和真机上都没广告显示。也没报错