jQuery UI Autocomplete with CI ??

[eluser]lexusgs430[/eluser]
Hey guys, was wondering if you could help me get my autocomplete search working. Im getting mad errors. Ive got it working as far as it looks like its looking stuff up but then in my firebug its just returning all sorts of errors.

Namely:

this.menu is undefined
this._trigger("open")}else this.close(...e:c};return e.extend({label:c.label||

Im thinking the problem is just in my javascript but not sure.

Code:

jq part = following

$().ready( function() {    
        
        $(".search").autocomplete({
            minLength: 5,
            source:
                function(req, add)
                {
                    $.ajax({
                        url: '<?php echo site_url('/search/lookup');?>',
                        dataType: 'json',
                        type: 'POST',
                        data: req,
                        success:    
                            function(data)
                            {
                                if(data.response =='true')
                                {
                                    add(data.message);
                                }
                            }
                    });
                },
            select:
                function(event, ui)
                {
                  $(this).end().val(ui.item.title);
                }
        });    
    });

------ model lookup = following (using the dmz datamapper library)

    function lookup_item($keyword)
    {
        $i = new Item();
        $i->like('itemTitle', $keyword);
        $results = $i->get();
        return $results;
    }

------ controller = following

    function lookup()
        {
            // process posted form data (the requested product)
            $keyword = $this->input->post('search');
            $data['response'] = 'false'; //Set default response
            $i = new Item();
            $query = $i->lookup_item($keyword); //Search DB
            if( ! empty($query) )
            {
                //print_r[$row];
                $data['response'] = 'true'; //Set response
                $data['message'] = array(); //Create array
                foreach( $query as $row )
                {
                    $data['message'][] = array( 'label'=> $row->id,
                                                'item'=> $row->itemTitle,
                                                'value'=> $row->itemTitle); //Add a row to array
                }
            }
            if(IS_AJAX)
            {
                echo json_encode($data); //echo json string if ajax request
            }
            else
            {
                $data['results'] = $query;
                $data['main_content'] = "search-results";
                $this->load->view('includes/template',$data); //Load html view of search results
            }

        }

any help much appreciated!