flutter - google_mobile_ads：未能加载广告：3

Question

这是我当前尝试加载广告的代码：

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

class HomePage extends StatelessWidget {
  HomePage({Key? key}) : super(key: key);

  final ad = BannerAd(
    adUnitId: BannerAd.testAdUnitId,
    request: AdRequest(),
    size: AdSize.banner,
    listener: BannerAdListener(),
  )..load();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Pokedex'),
      ),
      body: Container(
        height: 50,
        child: AdWidget(
          ad: ad,
        ),
      ),
    );
  }
}

这是我初始化 MobileAds 的 main.dart 文件：

void main() {
  WidgetsFlutterBinding.ensureInitialized();

  MobileAds.instance.initialize();

  // setting prefered orientations
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
  ]);

  runApp(const MyApp());
}

广告只是没有加载，这是错误：

我不知道出了什么问题。

标签： flutterdartgooglemobileads