get_category_link just gives back the root-dir

I use a cool plugin from siteflickr to insert a random category and random posts out of this cat into my blog (see it working on the frontpage of https://www.bittekunst.de). The only problem is: The category isn′t linked yet. I wanted to change that by myself, but all I managed to do is to get known to the get_category_link-Function and that one always gives back a link to the root (www.bittekunst.de/category). I read on this reference site that the reason is a non-existing category ID. But I don′t get the point.

So, here′s the original code of the plugin:

function random_category_and_posts($type=”ul”, $beforeHead=”h2″, $afterHead=”h2″, $numPosts=”5″, $categoryID = ”, $includeExcerpt=false, $customField=””, $customValue=””)
{
global $wpdb; // Global wordpress variables

// set the default before and after values
if ( $beforeHead == ” ) $beforeHead = ‘h2’;
if ( $afterHead == ” ) $afterHead = ‘h2’;
if ( $numPosts == ” ) $numPosts = ‘5’;

// Get a random category
$category = random_category($categoryID);

if ( $category[‘post_count’] < $numPosts ) {
$numPosts = $category[‘post_count’];
}

$articles = random_posts($category[‘id’], $includeExcerpt, $numPosts, $customField, $customValue);

// Display the category name
$result = (“<” . $beforeHead . “>Was Neues? Zum Beispiel ” . $category[‘name’] . “:</” . $afterHead . “>\n”);

My Change:
I tried different things, e.g. inserted
$the_cat_adress = get_category_link($category->cat_ID); just before the line which prints out the category-name (I inserted <a href=-command in that line). I tried it via direct-function call in that printing-line. I tried the Variables $category_id and $category. And I don′t know what to do know..

Anybody knows?

Thanks!
David