Facebook Audience Network not showing real ads without mediation but test Ads are showing

Question

I try to use Facebook Audience Network on my android app without mediation but it is not showing real ads and test Ads are showing.

Any idea? I'm so stuck with it.

browser_activity.java

  AudienceNetworkAds.initialize(this);

  adView = new AdView(this, "718544759324520_718567389322257",AdSize.BANNER_HEIGHT_50);

  LinearLayout adContainer = (LinearLayout) findViewById(R.id.adViewFAN);

  adContainer.addView(adView);

  adView.loadAd();

activity_browser.xml

<LinearLayout
    android:id="@+id/adViewFAN"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:orientation="vertical"
    app:layout_constraintBottom_toBottomOf="parent"
    android:layout_centerHorizontal="true"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/swapToRefresh"
    app:adUnitId="@string/ad_banner_id"
    />

image SS No mediation platform (Audience Network only)