Audience Network Facebook

please i finish my game and i want to add the ads of the audience network facebook for Instant Games
but i can't, i add 2 plugins (facebook and audience network ) i create tow function LoadInterstitial() and ShowInterstitial() but i can't show the ads in my game when the player lose or winning how i can solve this probelem.

Code :

public void LoadInterstitial()
{
// Create the interstitial unit with a placement ID (generate your own on the Facebook app settings).
// Use different ID for each ad placement in your app.
this.interstitialAd = new InterstitialAd("Interstitial Placement ID");

this.interstitialAd.Register(this.gameObject);

// Set delegates to get notified on changes or when the user interacts with the ad.
this.interstitialAd.InterstitialAdDidLoad = (delegate() {
Debug.Log("Interstitial ad loaded.");
this.isLoaded = true;
this.didClose = false;
});
interstitialAd.InterstitialAdDidFailWithError = (delegate(string error) {
Debug.Log("Interstitial ad failed to load with error: " + error);
});
interstitialAd.InterstitialAdWillLogImpression = (delegate() {
Debug.Log("Interstitial ad logged impression.");
});
interstitialAd.InterstitialAdDidClick = (delegate() {
Debug.Log("Interstitial ad clicked.");
});

this.interstitialAd.interstitialAdDidClose = (delegate() {
Debug.Log("Interstitial ad did close.");
this.didClose = true;
if (this.interstitialAd != null) {
this.interstitialAd.Dispose();
}
});

#if UNITY_ANDROID
/*
* Only relevant to Android.
* This callback will only be triggered if the Interstitial activity has
* been destroyed without being properly closed. This can happen if an
* app with launchMode:singleTask (such as a Unity game) goes to
* background and is then relaunched by tapping the icon.
*/
this.interstitialAd.interstitialAdActivityDestroyed = (delegate() {
if (!this.didClose) {
Debug.Log("Interstitial activity destroyed without being closed first.");
Debug.Log("Game should resume.");
}
});
#endif

// Initiate the request to load the ad.
this.interstitialAd.LoadAd();
}

// Show button
public void ShowInterstitial()
{
if (this.isLoaded) {
this.interstitialAd.Show();
this.isLoaded = false;
}
}


public void StartGame()
{

LoadInterstitial ();
ShowInterstitial ();


//Code Games
}

 

i have the same problem, i dotn't know what i miss in the code