not working, edited template.php but still the same title

Hello congratulation for your work. I'm in drupal 5.8 and custom template. Trying to use this great module.
It is not working even after editing of code in template.php (I think documentation is not too clear for pleople not used with php codes and variables, number of lines to modify should be more clear)

I've edited the template.php and now it looks like:

function _phptemplate_variables($hook, $vars) {
  if ($hook == 'page') {

    if ($secondary = menu_secondary_local_tasks()) {
      $output = '<span class="clear"></span>';
      $output .= "<ul class=\"tabs secondary\">\n". $secondary ."</ul>\n";
      $vars['tabs2'] = $output;
    }

    // Hook into color.module
    if (module_exists('color')) {
      _color_page_alter($vars);
    }
	
	//page title
	if (module_exists('page_title')) {
    $vars['head_title'] = page_title_page_get_title();
  } 

    return $vars;
  }
  return array();
}

trying the second method mentioned , i've seen that in our template file page-default.tpl.php the TITLE TAG is declared in this way : print $title