How to use admob on MG 3.6?

Hello,
please, tell me how to use AdMob on MG 3.6?
I try to use admob but I dont see any ads. What I do wrong?

public class Activity1 : Microsoft.Xna.Framework.AndroidGameActivity
{
private AdView bannerAd;
public AdView BannerAd
{
get { return bannerAd; }
}
private static InterstitialAd interstitial;
private const string bannerID = “ca-app-pub-59”;
private const string interstitialID = “ca-app-pub-59”;
private const string testDeviceID = “7772”;
private LinearLayout ll;
private FrameLayout fl;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        HalmaAndroid.GAService.GetGASInstance().Initialize_NativeGAS(this);
        var g = new Game1();

        //Game engine activity variable
        //g.activity = this;
        interstitial = AdWrapper.ConstructFullPageAd(this, interstitialID);
        fl = new FrameLayout(this);
        fl.AddView((View)g.Services.GetService(typeof(View)));
        SetContentView(fl);
        
        g.Run();
    }
    public void CreateBannerAd()
    {
        if (ll == null)
        {
            HideBannerAd();
            ll = new LinearLayout(this);
            ll.Orientation = Orientation.Horizontal;
            ll.SetGravity(GravityFlags.Left | GravityFlags.Bottom);
            bannerAd = new AdView(this);
            bannerAd.AdSize = AdSize.Banner;
            bannerAd.AdUnitId = bannerID;
            ll.AddView(bannerAd);
            fl.AddView(ll);
        }
        bannerAd.CustomBuild(testDeviceID);
    }
    public void HideBannerAd()
    {
        if (ll != null)
        {
            fl.RemoveView(ll);
            ll.RemoveView(bannerAd);
            bannerAd.Dispose();
            bannerAd = null;
            ll.Dispose();
            ll = null;
        }
    }
    public void ShowInterstitialAd()
    {
        RunOnUiThread(() =>
        {
            if (interstitial.AdListener != null)
                interstitial.AdListener.Dispose();
            interstitial.AdListener = null;
            var intlistener = new adlistener();
            intlistener.AdLoaded += () => { if (interstitial.IsLoaded) interstitial.Show(); };
            interstitial.AdListener = intlistener;
            interstitial.CustomBuild(testDeviceID);
        });
    }

public static class AdWrapper
{
public static InterstitialAd ConstructFullPageAd(Context con, string UnitID)
{
var ad = new InterstitialAd(con);
ad.AdUnitId = UnitID;
return ad;
}
public static AdView ConstructStandardBanner(Context con, AdSize adsize, string UnitID)
{
var ad = new AdView(con);
ad.AdSize = adsize;
ad.AdUnitId = UnitID;
return ad;
}
public static InterstitialAd CustomBuild(this InterstitialAd ad, string testDeviceID)
{
var requestbuilder = new AdRequest.Builder()
.AddTestDevice(AdRequest.DeviceIdEmulator)
.AddTestDevice(testDeviceID)
.Build();
ad.LoadAd(requestbuilder);
return ad;
}
public static AdView CustomBuild(this AdView ad, string testDeviceID)
{
var requestbuilder = new AdRequest.Builder()
.AddTestDevice(AdRequest.DeviceIdEmulator)
.AddTestDevice(testDeviceID)
.Build();
ad.LoadAd(requestbuilder);
return ad;
}
}

// show fullscreen banner
var act = (Activity1)Game1.Activity;
act.ShowInterstitialAd();

//show ads
var act = (Activity1)Game1.Activity;
act.CreateBannerAd();

//hide ads
var act = (Activity1)Game1.Activity;
act.HideBannerAd();

in AndroidManifest.xml

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
	<uses-permission android:name="android.permission.INTERNET" />
	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
	<!-- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> -->
	<!-- Optional -->
	<!-- <uses-permission android:name="android.permission.GET_ACCOUNTS" /> -->
	<application android:label="AG_Checkers" android:icon="@drawable/Icon">
		<activity android:name="com.google.android.gms.ads.AdActivity" android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize" />
	</application>