我用javascript+webservice获取省份信息，可是没反应？请教高手了

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">
        function diqu(){
            var URL = "http://webservice.webxml.com.cn/WebServices/WeatherWS.asmx";
            var data;
            data = '<?xml version="1.0" encoding="utf-8"?>';
            data = data + '<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">';
            data = data + '<soap:Body>';
            data = data + '<getRegionProvince xmlns="http://WebXml.com.cn/">';
            data = data + '</getRegionProvince>';
            data = data + '</soap:Body>';
            data = data + '</soap:Envelope>';
            var xmlhttp;
            if (window.XMLHttpRequest) {// code for all new browsers
                xmlhttp = new XMLHttpRequest();
            }
            else if (window.ActiveXObject) {// code for IE5 and IE6
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xmlhttp.Open("POST", URL, true);
            alert(xmlhttp);
            xmlhttp.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
            xmlhttp.setRequestHeader("Content-Length",data.length);
            xmlhttp.setRequestHeader("SOAPAction", "http://WebXml.com.cn/getRegionProvince");
            xmlhttp.Send(data);
            document.getElementById("data").innerHTML = xmlhttp.responseXML;
        }
    </script>
</head>
<body>
      <div>
        <input id="One" type="button" value="点击" onclick="diqu()" />
    </div>
     <div id="data">
    </div>
</body>
</html>