title: javascript jquery datatables undefined is not a function
body: <p>I'm following the jquery datatables tutorial for adding child tables to display after a click.</p>
  
  <pre class="lang-js prettyprint-override"><code>var table = $("#equipment_table").dataTable(
  {
       "paging":   false,
       "ordering": false,
       "info":     false
  });
  $('#equipment_table tbody').on('click', 'td .pickup_button', function(){
      alert("clickee");
      var tr = $(this).closest('tr');
      var row = table.row(tr);
      if(row.child.isShown()){
          //open , close it
          row.child.hide();
          tr.removeClass('shown');
      }else {
          row.child( buildChild(tr.attr('id'))).show();
          tr.addClass('shown');
      }
  });
  </code></pre>
  
  <p>and here's the html button definition in php</p>
  
  <pre class="lang-php prettyprint-override"><code>    echo '&lt;td&gt; &lt;button class="delivery_button" id="'.$eid.'"&gt; Delivery Status &lt;/button&gt; &lt;/td&gt;';
      echo '&lt;td&gt; &lt;button class="pickup_button" id="'.$eid.'"&gt; Pickup Status &lt;/button&gt; &lt;/td&gt;';
      echo '&lt;/tr&gt;';
  }
  echo '&lt;/tbody&gt;';
  </code></pre>
  
  <p>after getting the click listener to work, i get this error</p>
  
  <pre><code>Uncaught TypeError: undefined is not a function 
  </code></pre>
  
  <p>on <code>var row = table.row(tr);</code> line</p>