title: Active Admin view to PDF
body: <p>I'm starting to develop in Ruby on Rails recently, therefore I consider myself beginner.</p>
  
  <p>I'm testing the Active Admin gem ( <a href="http://activeadmin.info/" rel="noreferrer">http://activeadmin.info/</a> ) and I found a problem when export a view to PDF.</p>
  
  <p>In the official documentation says how to customize the download links (<a href="http://activeadmin.info/docs/3-index-pages.html" rel="noreferrer">http://activeadmin.info/docs/3-index-pages.html</a>, it is at the end of the document) but does not work for me.</p>
  
  <p>When I put the following line of code:</p>
  
  <pre><code>Mymodel ActiveAdmin.register do
    index: download_links =&gt; [: pdf]
  end
  </code></pre>
  
  <p>The result is a link to localhost:3000/admin/mymodel.pdf and the following error displays: "Failed to load PDF document".</p>
  
  <p>two questions:</p>
  
  <ol>
  <li>What do you suggest?</li>
  <li>Could you give an example?</li>
  </ol>
  
  <p>I would be very grateful.</p>