Admob仅加载测试广告

Question

我试图在我的应用程序中添加广告，但不幸的是，它仅加载测试！ 我使用了这个库https://github.com/marcojak/MTAdmob，所以我的MinActivity.cs

protected override void OnCreate(Bundle savedInstanceState)
{
    TabLayoutResource = Resource.Layout.Tabbar;
    ToolbarResource = Resource.Layout.Toolbar;

    base.OnCreate(savedInstanceState);

    Xamarin.Essentials.Platform.Init(this, savedInstanceState);
    global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
    MobileAds.Initialize(this, "here is my app id");
    LoadApplication(new App());
}

AndroidMAndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.samplemtadmob">
    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="28" />
    <application android:label="SampleMTAdmob.Android">
      <meta-data android:name="com.google.android.gms.ads.APPLICATION_ID" android:value="my app-id"/>
      <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version"/>
      <activity android:name="com.google.android.gms.ads.AdActivity" android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize" android:theme="@android:style/Theme.Translucent" />
    </application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
</manifest>

我试图用加载奖励视频

CrossMTAdmob.Current.LoadRewardedVideo("ca-app-pub-2774421889203876/4315339018");

Google还发送了我的电子邮件 Your account is approved Congratulations! We've verified your account information and your ad serving is enabled. 但是我的应用仅加载测试广告。