Admob real ads not showing on flutter app but java app works

Question

First I created android app using java and admob real ads showing perfectly. Then I create another android app using flutter, I run with test ads first and that works fine. But then I use the same unit id and app id but real ads not showing on flutter app.

main.dart:

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'package:provider/provider.dart';

import 'ad_state.dart';
import 'home.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  final initFuture = MobileAds.instance.initialize();
  final adState = AdState(initFuture);

  runApp(
    Provider.value(
      value: adState,
      builder: (context, child) => MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: HomePage(),
    );
  }
}

home.dart

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'package:provider/provider.dart';

import 'ad_state.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  BannerAd banner;

  @override
  void initState() {
    super.initState();
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();

    final adState = Provider.of<AdState>(context);
    adState.initialization.then((status) {
      setState(() {
        banner = BannerAd(
          size: AdSize.banner,
          adUnitId: adState.bannerAdUnitId,
          listener: adState.bannerAdListener,
          request: AdRequest(),
        )..load();
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Admob"),
      ),
      body: Container(
        child: ListView(
          children: [
            Text("Hello World"),
            if (banner == null)
              SizedBox(height: 50)
            else
              Container(
                height: 50,
                child: AdWidget(
                  ad: banner,
                ),
              ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          print("Hello World");
        },
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

ad_state.dart:

import 'package:google_mobile_ads/google_mobile_ads.dart';

class AdState {
  Future<InitializationStatus> initialization;

  AdState(this.initialization);

  String get bannerAdUnitId => '<Banner_Unit_ID>';

  BannerAdListener get bannerAdListener => _adListener;

  BannerAdListener _adListener = BannerAdListener(
    // Called when an ad is successfully received.
    onAdLoaded: (Ad ad) => print('Ad loaded.'),
    // Called when an ad request failed.
    onAdFailedToLoad: (Ad ad, LoadAdError error) {
      // Dispose the ad here to free resources.
      ad.dispose();
      print('Ad failed to load: $error');
    },
    // Called when an ad opens an overlay that covers the screen.
    onAdOpened: (Ad ad) => print('Ad opened.'),
    // Called when an ad removes an overlay that covers the screen.
    onAdClosed: (Ad ad) => print('Ad closed.'),
    // Called when an impression occurs on the ad.
    onAdImpression: (Ad ad) => print('Ad impression.'),
  );
}

Following Error shows: Ad failed to load: LoadAdError(code: 3, domain: com.google.android.gms.ads, message: No ad config., responseInfo: ResponseInfo(responseId: null, mediationAdapterClassName: , adapterResponses: []))

Answer 1

I have uploaded app on play store. After uploading on play store ads are showing successfully.