Admobs奖励广告无法加载

我一直在遵循Google的指南（https://developers.google.com/admob/android/rewarded-video）关于在我的应用上安装奖励广告，但尽管收到了成千上万的请求（如在admob报告中所示），但没有一个奖励广告投放 .

以下是奖励广告的活动的一些摘录 .

import com.google.android.gms.ads.AdListener;
 import com.google.android.gms.ads.AdRequest;
 import com.google.android.gms.ads.AdView;
 import com.google.android.gms.ads.InterstitialAd;
 import com.google.android.gms.ads.MobileAds;
 import com.google.android.gms.ads.reward.RewardItem;
 import com.google.android.gms.ads.reward.RewardedVideoAd;
 import com.google.android.gms.ads.reward.RewardedVideoAdListener;

 public class Ji extends Activity implements RewardedVideoAdListener {


    //reward ad
    private RewardedVideoAd mRewardedVideoAd;

    //ad     
    private InterstitialAd interstitial;

@Override
    protected void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);
  setContentView(R.layout.ji);


  MobileAds.initialize(this, "THE_APP_ID");


  //reward ad
  mRewardedVideoAd = MobileAds.getRewardedVideoAdInstance(this);
  mRewardedVideoAd.setRewardedVideoAdListener(this);
  //this is where it occurs
  loadRewardedVideoAd();


    @Override
    protected void onDestroy() {
       mRewardedVideoAd.destroy(this);
       super.onDestroy();

    }


    @Override
    protected void onResume() {
       mRewardedVideoAd.resume(this);
       super.onResume();

    }

    @Override
    protected void onPause() {
       mRewardedVideoAd.pause(this);
       super.onPause();
    }


    private void loadRewardedVideoAd() {
       //actual ad
       mRewardedVideoAd.loadAd("THE_AD_ID",
        new AdRequest.Builder().build());
    }


    @Override
    public void onRewardedVideoAdLoaded() {
       // Toast.makeText(this, "onRewardedVideoAdLoaded", Toast.LENGTH_SHORT).show();
       erco = 200;

    }

    @Override
    public void onRewardedVideoAdOpened() {
 //        Toast.makeText(this, "onRewardedVideoAdOpened", Toast.LENGTH_SHORT).show();
    }

         @Override
         public void onRewardedVideoStarted() {
 //        Toast.makeText(this, "onRewardedVideoStarted", Toast.LENGTH_SHORT).show();
         }

    @Override
    public void onRewardedVideoAdClosed() {
 //        Toast.makeText(this, "onRewardedVideoAdClosed", Toast.LENGTH_SHORT).show();
 // Load the next rewarded video ad.
       loadRewardedVideoAd();


    }


    @Override
    public void onRewarded(RewardItem rewardItem) {
 //            Toast.makeText(this, "onRewarded! currency: " + rewardItem.getType() + "  amount: " +
 //                    rewardItem.getAmount(), Toast.LENGTH_SHORT).show();

   }

    @Override
    public void onRewardedVideoAdLeftApplication() {
       //      Toast.makeText(this, "onRewardedVideoAdLeftApplication",
       //              Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onRewardedVideoAdFailedToLoad(int errorCode) {
       //     Toast.makeText(this, "onRewardedVideoAdFailedToLoad " + errorCode, Toast.LENGTH_SHORT).show();
       erco = errorCode;
    }

    @Override
    public void onRewardedVideoCompleted() {
    }



    private void d_ao() {

  final Dialog ploc = new Dialog(context);
  Window window = ploc.getWindow();
  window.setLayout(ViewGroup.LayoutParams.WRAP_CONTENT,           ViewGroup.LayoutParams.WRAP_CONTENT);
  window.setGravity(Gravity.CENTER);

  ploc.setContentView(R.layout.d_ao);

  Button baye = (Button) ploc.findViewById(R.id.ba_yes);
  Button bano = (Button) ploc.findViewById(R.id.ba_no);


  baye.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {


           mRewardedVideoAd.show();

           //reward the user after the ad            

        ploc.dismiss();


     }
  });

  bano.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {

        ploc.dismiss();


     }
  });

  ploc.show();

}

我按照admob准则将相关的sdk行插入gradle文件中 .

目前，我正在尝试设置应用以显示插页式广告，以防奖励未显示，但由于某些奇怪的原因，插页式广告也不会显示，尽管在其他活动中运作良好 .

此外，我还有一个问题，一旦奖励广告显示，奖励金额和奖励项目“奖励”在应用程序中的含义 . 目前，我的目的是让用户在显示奖励视频后通过启用按钮获得添加的功能 . 这只发生一次 . 我该如何实现？此外，在我的应用程序中，没有提及“奖励”项目或其在app中与admob有关的金额 .

请帮忙 .