Ads not comming in admob free plugin

launchReward() {
let rewardConfig: AdMobFreeRewardVideoConfig = {
isTesting: false,
autoShow: false,
id: “id”
};
this.admob.rewardVideo.config(rewardConfig);
this.admob.rewardVideo.prepare().then((res) => {
this.admob.rewardVideo.show().then(response => {
alert(response);
})
});
}

config .xml

<plugin name=“cordova-plugin-admob-free” spec="^0.21.0">

“dependencies”: {
@angular/animations”: “5.2.11”,
@angular/common”: “5.2.11”,
@angular/compiler”: “5.2.11”,
@angular/compiler-cli”: “5.2.11”,
@angular/core”: “5.2.11”,
@angular/forms”: “5.2.11”,
@angular/http”: “5.2.11”,
@angular/platform-browser”: “5.2.11”,
@angular/platform-browser-dynamic”: “5.2.11”,
@ionic-native/admob-free”: “^4.16.0”,
@ionic-native/admob-plus”: “^4.16.0”,
@ionic-native/core”: “~4.15.0”,
@ionic-native/splash-screen”: “~4.15.0”,
@ionic-native/status-bar”: “~4.15.0”,
@ionic/storage”: “2.2.0”,
“cordova-admob-sdk”: “^0.20.1”,
“cordova-android”: “7.0.0”,
“cordova-plugin-admob-free”: “^0.21.0”,
“cordova-plugin-device”: “^2.0.2”,
“cordova-plugin-ionic-keyboard”: “^2.1.3”,
“cordova-plugin-ionic-webview”: “^2.2.0”,
“cordova-plugin-splashscreen”: “^5.0.2”,
“cordova-plugin-statusbar”: “^2.4.2”,
“cordova-plugin-whitelist”: “^1.3.3”,
“cordova-promise-polyfill”: “0.0.2”,
“ionic-angular”: “3.9.2”,
“ionicons”: “3.0.0”,
“rxjs”: “5.5.11”,
“sw-toolbox”: “3.6.0”,
“zone.js”: “0.8.26”
},
“devDependencies”: {
@ionic/app-scripts”: “3.2.0”,
@ionic/lab”: “1.0.11”,
“typescript”: “~2.6.2”
},
“description”: “An Ionic project”,
“cordova”: {
“plugins”: {
“cordova-plugin-whitelist”: {},
“cordova-plugin-statusbar”: {},
“cordova-plugin-device”: {},
“cordova-plugin-splashscreen”: {},
“cordova-plugin-ionic-webview”: {
“ANDROID_SUPPORT_ANNOTATIONS_VERSION”: “27.+”
},
“cordova-plugin-ionic-keyboard”: {},
“cordova-plugin-admob-free”: {
“ADMOB_APP_ID”: “ca-app-pub-4431981785018302~4285091806”
}
},
“platforms”: [
“android”
]
}