title: Datatable Button Error: Uncaught Unknown button type: print
body: <p>I've got a very strange problem with the print button on a datatable I couldn't find a solution for.</p>
  
  <p>The strange thing is that I've already used the print button in datatables on different pages.</p>
  
  <p>At the moment I am working on a ruby on rails project, including datatables with the jquery-datatables-rails gem, version 3.3.0.</p>
  
  <p>Additionally, I include the CSS and the JS file for the buttons by referencing the file path in the assets pipeline (<code>dataTables.buttons.min</code> and <code>buttons.datatables.min.css</code>).</p>
  
  <p>All the files are loaded without any problem or error message. 
  Initialising of the datatable works as well, but then I add the option below:</p>
  
  <pre><code>dom: 'Bfrtip'
  buttons: [ 'print' ]
  </code></pre>
  
  <p>to the initializer, it causes to crash with the error message below: </p>
  
  <blockquote>
    <p>Uncaught Unknown button type: print dataTables.buttons.min.js?body=1:18</p>
  </blockquote>
  
  <p>Unfortunately I could not find anyone that has the same problem in the internet.</p>
  
  <p>I followed the instructions on <a href="https://datatables.net/extensions/buttons/" rel="noreferrer">https://datatables.net/extensions/buttons/</a>, adding the two files to my page. </p>
  
  <p>Also, when I try to use the <em>excel</em> button instead of the <em>print</em> button, no error message appears, but still no button is showing up.</p>
  
  <p>The <code>div.dt-buttons</code> stays empty. </p>
  
  <p>How can I resolve this?</p>