$header = array(
    theme('table_select_header_cell'),
    array('data' => t('Username'), 'field' => 'u.name'),
    array('data' => t('ID'), 'field' => 'u.uid'), // ต้องเป็น uid
    array('data' => t('Status'), 'field' => 'u.status'),
    t('Roles'),
    array('data' => t('Member for'), 'field' => 'u.created', 'sort' => 'desc'),
    array('data' => t('Last access'), 'field' => 'u.access'),
    t('Operations')
  );
...
...
      $rows[] = array(
        drupal_render($form['accounts'][$key]),
        drupal_render($form['name'][$key]),
        $key, // $key เป็น uid
        drupal_render($form['status'][$key]),
        drupal_render($form['roles'][$key]),
        drupal_render($form['member_for'][$key]),
        drupal_render($form['last_access'][$key]),
        drupal_render($form['operations'][$key]),
      );