I used AdMob free for Ionic 4 app AdMob works fine during isTesting true But not working on Production mode when isTesting false

Ionic Framework
1

showBannerAd() {
let bannerConfig: AdMobFreeBannerConfig = {
autoShow: true,
isTesting: false,
id: “ca-app-pub-3940256099942544/6300978111”
};
this.admobFree.banner.config(bannerConfig);
this.admobFree.banner.prepare().then(() => {
}).catch(e => alert(e));
}