sort handler

Hi

I have read the link http://drupal.org/node/357079, but my custom sort handler is not getting called.

Implemented is the following empty sort handler. However, when I select the activated table-style column to sort, this sort handler is ignored.
<?php
class region_views_handler_sort extends views_handler_sort {
function query() {
parent::query();
drupal_set_message('region_id custom query()');
}

function options_form(&$form, &$form_state) {
parent::options_form($form, $form_state);