Navigation menu and Mandigo

Hello,

I’m using wordpress 3.0 with the mandigo v1.42 theme and I would like to know how to show the sub-categories or/and the sub-menus for the personnalised menus.
To show categories, I added thes line of code on header.php:
<?php wp_list_categories('title_li=&hierarchical=true'); ?>
Just after this:

<?php
	// wordpress pages, minus the ones excluded in the theme options
	wp_list_pages(
		array(
			'sort_column' => 'menu_order',
			'depth'       => ($mandigo_options['header_navigation_no_submenus'] ? 1 : 0),
			'title_li'    => '',
			'exclude'     => @implode(',', $mandigo_options['header_navigation_exclude_pages']),
		)
	);
	// if you want to add custom static links at the end, use something similar to the following
	// <li class="page_item"><a href="https://whatever.com/">Go somewhere</a></li>
	// and put it right before the closing </ul>
?>

As I said, the mother categories are showen but the sub-categories don’t to!
Any help?

Thanks!