title: Admob interstitial ads - Cannot present interstitial. It is not ready
body: <p>Is this code correct to implement an interstitial ad? </p>
  
  <p><img src="https://i.stack.imgur.com/xiHFb.png" alt="enter image description here"></p>
  
  <p>Because when I launch it I get this,</p>
  
  <pre><code>&lt;Google&gt; Cannot present interstitial.  It is not ready.
  </code></pre>