jquery ui autocomplete not showing result

so i'm using jquery ui autocomplete instead of combobox to make it easier for my users to select hundreds of products from database.

$(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.item.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);
    };  
});

firebug tells me that php successfully generates requested data, like below.

[
    {"product_id":"92","product_code":"TURE3052","product_name":"Choose Your Own Adventure"},
    {"product_id":"89","product_code":"UMPS3447","product_name":"Goosebumps"},
    {"product_id":"15","product_code":"ROSE7302","product_name":"The Name of the Rose"},
    {"product_id":"开发者_开发技巧34","product_code":"LIFE1226","product_name":"The Purpose Driven Life"}
]

but somehow, the result does not show.

any ideas?

i copied parts of the codes from http://jqueryui.com/demos/autocomplete/#custom-data. i have tested the example and it worked.

ok, i don't quite understand how and why, but it so happened that i need to create clones of the autocomplete textbox. for that purpose, i use live() in order for jquery to catch the event of new clone. i modify the above code to look like below:

$(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.item.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);
        };  
    })
});

as i say, i don't understand how and why, but the autocomplete result does show up. felt a little relieved. but since it is a must for me to understand my own work, i think i have to figure out the explanation.

ideas?