[Plugin: Projectmanager] Show category breadcrumb

I tried to get a breadcrumb-like navigation containing the category hierarchy.

Therefore I wrote the following code into a file called crumb.php:

if($dataset){
    $cats = $projectmanager->getSelectedCategoryIDs($dataset);
    foreach($cats as $cat){
        echo get_category_parents($cat, TRUE, ' » ');
        echo $dataset->name;
    }
}

I put it into my customized dataset.php like:

<?php if ( $backurl ) : ?>
<div class="breadcrumb"><?php include 'crumb.php'; ?></div><div class="backurl"><a href='<?php echo $backurl ?>'><?php _e('Zur&uuml;ck zur Liste', 'projectmanager') ?></div><br style="clear:both;"/>
<?php endif; ?>

Everything went well, but the category-links won’t show up the article from the projectmanager.

Does anybody know how to achieve this?