Colspan ruins plugin's work

[nightrider77]

So simple table, and plugin doesn't work

  <table id="tbl2" class="ui celled table" data-resizable-columns-id="demo-table-v2">
    <thead>
      <tr>
        <th data-resizable-column-id="a1" colspan="2">Actions</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td data-resizable-column-id="a2">Treeview</td>
        <td data-resizable-column-id="a3">Filters</td>
      </tr>
    </tbody>
  </table>