WOZ Sidebars edition - display top-level categories only

[secondnature]

Forgive me if this is a Wordpress issue but I've scoured their forums and this one and I can't find what I need.

Using WOZ Sideboxes only edition on ZC 1.5.

My blog categories show up fine and I can turn on/off option counts and hierarchy using the wp commands included in the install file tpl_wp_cats.php.

This is what's in the file. I've added the depth command and it does nothing. I've also tried deprecated commands such as 'children' with no luck

  $content = "";

if($woz_install){
    
  //start wp output
  ob_start();
  wp_list_cats('sort_column=name&optioncount=0&hierarchical=0&depth=1');
  $out = ob_get_clean();
  //end wp output

  $content .= '<div id="' . str_replace('_', '-', $box_id . 'Content') . '" class="sideBoxContent">';
  $content .= '<ul>'.$out.'</ul>';
    
} 

Please point this novice in the right direction...