can’t get ‘&hierarchical=0’ to work

I’m running WordPress 2.0.4, and having a small problem with a category list.

I’m using the following to list sub-categories from a particular category:

<?php wp_list_cats('sort_column=name&optioncount=1&child_of=13&exclude=12'); ?>

this works except I would like the list not to be hierarchical.

When I then add &hierarchical=0 , i.e. wp_list_cats('sort_column=name&optioncount=1&child_of=13&exclude=12&hierarchical=0') the list shows all categories not just the children of category 13, so it seems by adding &hierarchical=0 I’m cancelling out all the other options.

Has anyone had the same problem or know of way to get around this?

It is not the display of the list that bothers me, as I can controll that with CSS. What bothers me is that when the list is hierarchical, it is not sorted properly, as it will list the parents alphabetically first, then the children alphabetically. So in some cases you end up with “c” coming before “a”, etc.

I’d be really grateful for any help you may be able to give.