title: jquery datatable excel export button not showing
body: <p>Hi i'm using Datatables js version <code>1.9.4</code> css version <code>1.9.4</code>. And initialize the data table using below code.</p>
  
  <p>Also added support js and css</p>
  
  <pre><code>&lt;script type="text/javascript" th:src="@{/resources/js/excel-export/dataTables.buttons.min.js}"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" th:src="@{/resources/js/excel-export/buttons.flash.min.js}"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" th:src="@{/resources/js/excel-export/jszip.min.js}"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" th:src="@{/resources/js/excel-export/buttons.html5.min.js}"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" th:src="@{/resources/js/excel-export/buttons.print.min.js}"&gt;&lt;/script&gt;
  &lt;link th:href="@{/resources/js/excel-export/buttons.dataTables.min.css}"
      type="text/css" rel="stylesheet" /&gt;
  
  var tblUnSubscribedKeys = $('#tblUnSubscribedKeys').DataTable({
                       "aoColumns" : [ null, null,null,null,null,null],
                       "processing": true,
                       "serverSide": true,
                       dom: 'Bfrtip',
                             buttons: [
                                 'excel'
                             ]
                   });
  </code></pre>
  
  <p>The problem is, the data on the table populated correctly. But the excel export button is not visible.</p>