NativeAd的充气视图

Question

我想在内部扩展存储NativeAd的视图。代码如下：

代码：

  public void insert_Native_ad()
    {
        boolean purchased_noAd = checked_purchase_ad();
        if (purchased_noAd)
        {

        }
        else
        {
            DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
            float deviceWidthInDp = displayMetrics.widthPixels / displayMetrics.density;
            int adWidth = (int)(deviceWidthInDp);

            final View inflated_item1 = getLayoutInflater().inflate(R.layout.inflated_view_native_ad, null, false);
            LinearLayout.LayoutParams params1 = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            params1.setMargins(Constants.SCREEN_W/20, 2, 0, 2);
            ((ViewGroup) ll_content).addView(inflated_item1, params1);

            RelativeLayout inflate_view = (RelativeLayout) inflated_item1.findViewById(R.id.inflate_view);

            MobileAds.initialize(getApplicationContext(), getString(R.string.app_id));                
            final NativeExpressAdView mAdView = new NativeExpressAdView(this);

            if (mAdView != null) {
                // prevents a crash on older devices
                mAdView.clearAnimation();
            }

            mAdView.setAdSize(new AdSize(adWidth, 250)); // AdSize(width, height),
            mAdView.setAdUnitId(getString(R.string.app_unitid));

            mAdView.setVideoOptions(new VideoOptions.Builder()
                    .setStartMuted(true)
                    .build());

            // The VideoController can be used to get lifecycle events and info about an ad's video asset.
            // One will always be returned by getVideoController, even if the ad has no video asset.
            mVideoController = mAdView.getVideoController();
            mVideoController.setVideoLifecycleCallbacks(new VideoController.VideoLifecycleCallbacks() {
                @Override
                public void onVideoEnd() {
                    Log.d(LOG_TAG, "Video playback is finished.");
                    super.onVideoEnd();
                }
            });

            // Set an AdListener for the AdView, so the Activity can take action when an ad has finished loading.
            mAdView.setAdListener(new AdListener() {
                @Override
                public void onAdLoaded() {
                    if (mVideoController.hasVideoContent()) {
                        Log.d(LOG_TAG, "Received an ad that contains a video asset.");
                    } else {
                        Log.d(LOG_TAG, "Received an ad that does not contain a video asset.");
                    }
                }
            });

            inflate_view.addView(mAdView);

            final AdRequest.Builder adReq = new AdRequest.Builder();
            final AdRequest adRequest = adReq.build();
            mAdView.loadAd(adRequest);
        }
    }

问题：

视图已成功膨胀，但内部未显示任何广告。有什么问题？