jquery ui autocomplete: clicking on list does nothing

i use jquery ui autocomplete and took the example from this link .

this is my modification:

$(function() {
    $(".autocomplete").live('keyup.autocomplete', function() {
        $(".autocomplete").autocomplete({
            source: function(request, response) {
                $.ajax({ 
                    'url': "http://localhost/project/index.php/product/search_data/",
                    'data': { 'txt_product_name': $('#txt_product_name').val()},
                    'dataType': "json",
                    'type': "POST",
                    'success': function(data){
                        response(data);
                    }
                })
            }, 
            minLength: 2,
            focus: function( event, ui ) {
                $(".txt_product_id").val(ui.item.product_id);
                return false;
            },
            select: function( event, ui ) {
                $( ".txt_product_id" ).val(ui.ite开发者_JS百科m.product_id);
                $( ".txt_product_code" ).val(ui.item.product_code);
                $( ".txt_product_name" ).val(ui.item.product_name);

                return false;
            }       
        }).data("autocomplete" )._renderItem = function( ul, item ) {
            return $( "<li></li>" )
                .data( "item.autocomplete", item )
                .append( "<a>" + item.product_code + "<br>" + item.product_name + "</a>" )
                .appendTo(ul);
        };  
    })
});

the code works fine. and for my own purpose, i revise _renderItem so the result will be displayed in colums:

        data("autocomplete" )._renderItem = function(table, item) {
            return $( "<tr></tr>" )
                .data("item.autocomplete", item)
                .append("<td><a>" + item.product_code + "</a></td><td><a>" + item.product_name + "</a></td>")
                .appendTo(table);
        };  

the suggestion list shows up everytime i type my entries. but unlike before, clicking on the list does nothing to txt_product_id, txt_product_code and txt_product_name.

what should i do? any suggestions will be welcomed.

thanks in advance.