来自PHP XML的Flash AS3数据未显示在datagrid中

Question

我的PHP代码正在从数据库中正确读取，我可以运行PHP代码并查看XML。在闪存中我没有错误，数据网格正确显示，但数据根本不存在。

PHP代码

mysql_connect('localhost', 'root', '');
mysql_select_db('menu');

$sql = "SELECT item_name, item_price FROM menu1";
$res = mysql_query($sql);

header('Content-Type: application/xml');

print "<root>";
while ($row = mysql_fetch_assoc($res)) {
print "<items><itemname>".$row['item_name']."</itemname><itemprice>".$row['item_price']."  </itemprice></items>";
}
print "</root>";

AS3代码

import fl.controls.DataGrid;
import fl.data.DataProvider;

var data_grid:DataGrid = new DataGrid();

data_grid.addColumn("itemname");
data_grid.addColumn("itemprice");
data_grid.width = 600;
data_grid.rowCount = 2;
data_grid.move(10, 70);
addChild(data_grid);

var dp:DataProvider;
var request:URLRequest = new URLRequest("localhost/menu3.php");

var url_loader:URLLoader = new URLLoader();
url_loader.addEventListener(Event.COMPLETE, completeHandler);
url_loader.load(request);

function completeHandler(event:Event):void {
    var ldr:URLLoader = event.currentTarget as URLLoader;

    var xmlDP:XML = new XML(ldr.data);

    dp = new DataProvider(xmlDP);
    data_grid.dataProvider = dp;
}