Unity Banner Ads failed to Load

Question

I have been trying to load Banner on Android studio Java, but It doesn't load, to my surprise Interstitial ads load well, Please I need help:

public class MainActivity extends AppCompatActivity {

    String GameID = "5525497";
    String ADID = "Interstitial_Android";
    Boolean TestMode = true;
    String topAdUnitId = "Banner_Android";
    BannerView topBanner;
    RelativeLayout topBannerView;
    Button Btn1;
    private BannerView bannerAd;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        UnityAds.initialize(MainActivity.this, GameID, TestMode, new IUnityAdsInitializationListener() {
            @Override
            public void onInitializationComplete() {
                Toast.makeText(MainActivity.this, "SDK Working", Toast.LENGTH_SHORT).show();

            }

            @Override
            public void onInitializationFailed(UnityAds.UnityAdsInitializationError error, String message) {
                Toast.makeText(MainActivity.this, "SDK not Working", Toast.LENGTH_SHORT).show();
            }
        });

        Btn1 = findViewById(R.id.btn1);
        Btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                
                UnityAds.load(ADID);
                UnityAds.show(MainActivity.this, ADID);
            }
        });

        topBanner = new BannerView(MainActivity.this, topAdUnitId, new UnityBannerSize(320, 50));
        topBannerView = findViewById(R.id.banner_top);
        LoadBannerAd(topBanner, topBannerView);
    }
    void LoadInterstitial(){
        if(UnityAds.isInitialized()){
            UnityAds.load(ADID);
        }
    }

    public void LoadBannerAd(BannerView bannerView, RelativeLayout bannerLayout) {
        // Request a banner ad:
        bannerView.load();
        // Associate the banner view object with the banner view:
        bannerLayout.addView(bannerView);
    }
}

The above is my code, Kindly check and see what I can do to make the banner Ads load successfully.