wp_list_cats problem with feed option

Hi, I would like to make use of wp_list_cats including “…&feeds=RSS” to show a list of all available RSS 2.0 feeds.

Normally it works like this:
wp_list_cats(‘feed=RSS’);
wp_list_cats(‘sort_column=name&optioncount=1&hide_empty=false&feed=RSS’);

Could it be possible that the RSS option does not work with PHP5?

All the other parameters work fine. But as soon as I add a name for the feed (…&feed=name) the function breaks.

This means that I can see the category list with:
wp_list_cats(‘sort_column=name&optioncount=1&hide_empty=false&feed=’);

But if I make use of this one:
wp_list_cats(‘sort_column=name&optioncount=1&hide_empty=false&feed=RSS’);
it doesn`t show up anything. No list, no feeds, no fun.

Any idea how to fix this?

For authors it works without any trouble:
wp_list_authors(‘exclude_admin=false&show_fullname=true&optioncount=1&feed=RSS’);

(Versions: PHP5, WordPress 2.0.5)