Plugin: Entry Categories

{exp:weblog:entries weblog="directory" dynamic="on" limit="1"}
  {exp:entry_cats entry_id="{entry_id}" invalid_input="alert"}

    Entry ID: {entry_id}<br>                <!-- this works -->
    Level0 ID: {level0_category0_cat_id}     <!-- this works -->
    Level1 ID: {level1_category0_cat_id}     <!-- this works -->


<!-- now i want to pass Level0 ID in to the child_categories extension: -->

{exp:child_categories parent="{level0_category0_cat_id}" weblog="directory"}
  {parent_category_start}
  <a href="http://{homepage}/category/{parent_category_url_title}/class=directory">{parent_category_name}</a>
  <ul id="directory">
    {parent_category_end}
    {child_category_start}
    <li><a href="http://{homepage}/listings/category/{child_category_url_title}/">{child_category_name}   ({entries_total})</a></li>
    {child_category_end}
    {/exp:child_categories} 
    </ul>

<!-- as a test, i output the value again after the child_categories call -->

    Entry ID: {entry_id}<br>                <!-- this works -->
    Level0 ID: {level0_category0_cat_id}     <!-- this works -->
    Level1 ID: {level1_category0_cat_id}     <!-- this works -->

{/exp:entry_cats}

{/exp:weblog:entries}