广告横幅未显示

Question

我想将Google admob添加到我的统一游戏中。 https://github.com/googleads/googleads-mobile-unity/releases 但是横幅没有出现

根据https://developers.google.com/admob/unity/start 我编写了简单的脚本，并从Google Admob控制台（https://apps.admob.com）获取标语和应用程序的ID。

    public class ADS : MonoBehaviour
    {  
    string ads_banner_id = "ca-app-pub-6807450626654540/6028463012";
    string appID = "ca-app-pub-6807450626654540~4860573772";

    BannerView bannerView;

    public void InitBanner()
    {
        Debug.Log("InitBanner");
        bannerView = new BannerView(ads_banner_id, AdSize.Banner, AdPosition.Bottom);
        AdRequest request = new AdRequest.Builder().Build();
        bannerView.OnAdLoaded += (sender, args) =>
        {
            Debug.Log("InitBanner OnAdLoaded : " + sender + "->" + sender.GetType() + "\nargs[" + args + "]");
            bannerView.Show();
        };
        bannerView.OnAdFailedToLoad += (sender, args) =>
        {
            Debug.Log("InitBanner OnAdFailedToLoad :" + args.Message);
        };

        bannerView.LoadAd(request);
    }


    void Start()
    {
        MobileAds.Initialize(appID);
    } 
}

统一Admob设置

Manifest:

    <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.google.unity.ads" android:versionName="1.0" android:versionCode="1">
    <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="19" />
    <application>
    <uses-library android:required="false" android:name="org.apache.http.legacy" />
    <!-- Your AdMob App ID will look similar to this sample ID: ca-app-pub-3940256099942544~3347511713 -->
    <meta-data android:name="com.google.android.gms.ads.APPLICATION_ID" android:value="ca-app-pub-6807450626654540~4860573772" />
    <meta-data android:name="com.google.android.gms.ads.AD_MANAGER_APP" android:value="true" />
    </application>
    </manifest>

和登录：

你能帮我吗？