title: Calling fnGetPosition on datatables.net throws "Cannot call method 'toUpperCase' of undefined" error
body: <p>I am trying to get the position of a row in datatables using the following code</p>
  
  <pre><code>var table = $('#UserInformationTable').dataTable();
  var row_id = table.fnGetPosition($('#row_' + id));
  table.fnDeleteRow(row_id);
  </code></pre>
  
  <p>The <code>$('#row_' + id)</code> is returning a tr.</p>
  
  <p>The <code>fnGetPosition</code> does not work. I am getting this error:</p>
  
  <blockquote>
    <p>TypeError: Cannot call method 'toUpperCase' of undefined</p>
  </blockquote>
  
  <p>What am I doing wrong?</p>