jQuery切换tbody

<th class="folder">

    $('table').each(function(){
        $('th.folder', this).bind('click', function(){
            $(this).closest('table').children('tbody').toggle();
        });
    });

下面是一些典型的HTML:

<table>
  <thead>
    <tr>
      <th>Title</th>
      <th class="type">Type</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <table>
          <thead>
            <tr>
              <th class="folder" colspan="2">Deal flow</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td>item 1</td>
              <td>image</td>
            </tr>
            <tr>
              <td>item 2</td>
              <td>image</td>
            </tr>
          </tbody>
        </table>
        <table>
          <thead>
            <tr>
              <th class="folder" colspan="2">Rejected deals</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td>item 3</td>
              <td>image</td>
            </tr>
            <tr>
              <td>item 4</td>
              <td>image</td>
            </tr>
          </tbody>
        </table>
      </td>
    </tr>
  </tbody>
</table>

好像不起作用,我不明白为什么!有什么想法吗?