wp_list_pages Active State

I need to style a navigation list generated by wp_list_pages using css. There will be multiple top level pages and multiple subnav pages.

For some reason when I use this:

<?php

global $post; 

if (is_page() && $post->post_parent ) {
	// This is a subpage
 wp_list_pages("title_li=&link_before=<h3>&link_after=</h3>&include=".$post->post_parent);
 wp_list_pages("title_li=&link_before=<h4>&link_after=</h4>&child_of=".$post->post_parent);

} else {
	// This is not a subpage
  wp_list_pages("title_li=&link_before=<h3>&link_after=</h3>&include=".$post->ID);
  wp_list_pages("title_li=&link_before=<h4>&link_after=</h4>&child_of=".$post->ID);
}

?>

I am not getting the class added on the li elements when the current page is active. All I get is li.page_item. When I click on a SUB-page the parent’s class changes to .current_page_ancestor .current_page_parent, but when clicking on the main nav item I get no class change. I looked into the post-template include file where the function is located, but I don’t see how they are creating those active classes.

Any ideas about what is going on?

Thanks!
Joe