title: AMP error: Missing supported structured data element
body: <p>I have an aggregator site for books. I created dedicated AMP (Accelerated Mobile Page) for each book.</p>
  
  <ul>
  <li>Example AMP URL: <code>http://konyvar.hu/amp/nicholas-sparks/az-utolso-dal</code></li>
  <li>Example canonical URL: <code>http://konyvar.hu/nicholas-sparks/az-utolso-dal</code></li>
  </ul>
  
  <p>In Google Webmaster Tools, I see the following error for this page:</p>
  
  <blockquote>
    <p>Missing supported structured data element</p>
  </blockquote>
  
  <p>Google offers me to <a href="https://developers.google.com/structured-data/testing-tool?url=http%253A%252F%252Fkonyvar.hu%252Famp%252Fnicholas-sparks%252Faz-utolso-dal" rel="nofollow">Open Test Tool</a>, but it says: </p>
  
  <blockquote>
    <p>All good</p>
  </blockquote>
  
  <p>Please help me, I have no idea, what I'm doing wrong.</p>