title: Admob interstitial ad won't display
body: <p>I used to display AdMob banner on my future apps, and I'd like to give a try to the interstitial ads.</p>
  
  <p>I checked the AdMob SDK for implementation, and I copied their example source because it was exactly  what I want (i.e. the interstitial shown when the activity launch).</p>
  
  <p>I tried it on emulator and on my Galaxy, no ad has been displayed.</p>
  
  <p>Here is the source code:</p>
  
  <pre><code>public class Asscreed extends Activity {
      private InterstitialAd interstitial;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_asscreed);
  
          // Create the interstitial.
          interstitial = new InterstitialAd(this);
          interstitial.setAdUnitId("ca-app-pub-6046034785851961/xxxxxx");
  
          // Create ad request.
          AdRequest adRequest = new AdRequest.Builder().build();
  
          // Begin loading your interstitial.
          interstitial.loadAd(adRequest);
      }
  
      // Invoke displayInterstitial() when you are ready to display an interstitial.
      public void displayInterstitial() {
          if (interstitial.isLoaded()) {
              interstitial.show();
          }
      }
  }
  </code></pre>
  
  <p>The imports are OK and the Google Play Services library is of course imported.</p>
  
  <p>I use this example:  <a href="https://developers.google.com/mobile-ads-sdk/docs/admob/advanced" rel="noreferrer">AdMob Android Guides - Interstitial Ad</a>.</p>
  
  <p>Could someone tell me what's wrong in my code?  </p>