Altering the reply form?

I' following the instrucitons at http://www.digett.com/2010/06/29/how-theme-comment-form-drupal-6 and added the following to the end of my basic's template.php

/**
* Implementation of hook_theme.
* Register custom theme functions.
*/

function basic_theme() {
  return array(
    'comment_form' => array(
      'arguments' => array('form' => NULL),
    ),
  );
}

/**
 * Customizations to the Comment form.
 */

function basic_comment_form($form) {
  return print_r($form); 
}

My theme registry is continue being refreshed, but nothing happens at the comment form?