[ATCK] can't rewrite phptemplate functions

Hello!

I'm building my style, which based on ATCK 2.2 and I can't rewrite any phptemplate functions on it. In Garland it works fine. I would rewrite breadcrumb function. I'm trying various functions names, for example: function apt_breadcrumb($breadcrumb), function apt_preprocess_breadcrumb($breadcrumb), function apt_preprocess_breadcrumb() etc. (apt is name of my style), but it doesn't works. Actually my function code is:

function apt_preprocess_breadcrumb($vars) {
	$vars['home'] = '<a href="'. $base_path .'" title="'. t('Home') .'">'. t('Home') .'</a>';
	$vars['title'] = strip_tags($title); // Remove HTML tags from title
	$vars['page'] = '<a href="'. $node->path .'" title="'. $vars['title'] .'">'. $vars['title'] .'</a>';
	
	if ($is_front) {
		$breadcrumb = $vars['home'];
	}
	else {
		$breadcrumb = $vars['home'] .' &#8250; '. $vars['page'];
	}
		
	return $breadcrumb;
}

In header.tpl.php I added: You are here: <?php echo $breadcrumb; ?> but still this function works like here.

Can anyone tell me how this function should looks?

PS. Sorry for my bad English :(