Wp_list_pages ‘include’ don’t allow sub_menu

Hi!
I’m trying to set up a submenu (child pages) to my menu (parent pages) of my blog.
I’m using this code:

<ul>
    <li class="soumenu">
			<?wp_list_pages('include=5,29,18,24&depth=2&title_li=' ); ?>
</li>
</ul>

But it’s not working…. Apparently, submenus and wp_list_pages(“include=id_page”) can’t work together.

Does someone have an idea to resolve my problem?

Thanks in advance!