CSS Dropdown – Showing Children

I am the webmaster for the site, http://www.cookingwithellen.com. I am having problems getting the children of the categories to display on the dropdown menu the site is using. Here is the part of the menu that shows the categories:

<li onmouseover="javascript:toggleLayer('aboutus');" onmouseout="javascript:toggleLayer('aboutus');"><a href= "#">Categories</a>
		<ul id="aboutus">
			<? wp_list_cats('title_li=&sort_column=name&style=list&children=true&hierarchical=true'); ?>
		</ul>
	</li>

I want the categories to not only display “A” but also its children, such as “a. – ” or “a. – “. Can someone show me what string needs to be entered for this to work?

Thanks!