Logical Problem With category and sub-category

[eluser]brandingdavid[/eluser]
Trying to show a category tree (with subcats and sub-subcats)

Using this code:

Code:

<?php
    $categories = get_categories();
    
    foreach($categories as $category) {
            // Print the top level category
            echo $category->title .'<br />';
            
            // get the sub categories
            $subcategories = get_categories($category->id);
            foreach($subcategories as $subcategory) {
                echo '- '. $subcategory->title. '<br />';
            }
        }
        
        function get_categories($parent = 0) {
            $this->db->where('parent', $parent);
            $query = $this->db->get('bin_location');
            return $query->result();
        }
    ?&gt;

Getting: Fatal error: Call to a member function on a non-object in /home/domains/public_html/system/application/views/frontpage_view.php on line 25

Anyone have any ideas why I am having this problem?