我致力于整合广告。但不幸的是，当我更新sdk到6.2.0广告没有加载（没有消息出现），但在同一个代码我改变sdk到5.+，广告加载和显示

implementation 'com.facebook.android:audience-network-sdk:6.2.0' [Not loaded]

implementation 'com.facebook.android:audience-network-sdk:5.+'   [Loaded and shown]

    adView = new AdView(this, MainActivity.this.getString(R.string.facebook_banner_id), AdSize.BANNER_HEIGHT_50);
            // Find the Ad Container
            LinearLayout adContainer = (LinearLayout) findViewById(R.id.banner_container);
            // Add the ad view to your activity layout
            adContainer.addView(adView);
            // Request an ad
            adView.loadAd();
            //AdUtils.showFBInterstitialads(MainActivity.this);
            AdListener adListener = new AdListener() {
                @Override
                public void onError(Ad ad, AdError adError) {
                    // Ad error callback
                    Toast.makeText(
                            MainActivity.this,
                            "Error: " + adError.getErrorMessage(),
                            Toast.LENGTH_LONG)
                            .show();
                    Log.i("Adloaded", "error" + adError.getErrorMessage());

                }

                @Override
                public void onAdLoaded(Ad ad) {
                    Log.i("Adloaded", "loaded");
                }

                @Override
                public void onAdClicked(Ad ad) {
                    // Ad clicked callback
                }

                @Override
                public void onLoggingImpression(Ad ad) {
                    // Ad impression logged callback
                }
            };
            // Request an ad
            adView.loadAd(adView.buildLoadAdConfig().withAdListener(adListener).build());

android应用程序已经有了5.+sdk。但正如现在facebook所说的“将你的sdk更新到最新版本”。所以我把sdk“5.+”改成了“6.2.0”，但是什么也没有出现。当我回去，改变sdk 5+再次加载和显示广告