求救：ajax 获取价问题

问：dropdownlist 中的值在页面中获取不到．．用request获取不到价
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="deledanwei.aspx.cs" Inherits="requar_deledanwei" %><!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 src="../js/JScript.js" type="text/javascript" ></script>
    <script src="../js/JScript2.js" type="text/javascript" ></script>
    <script type="text/javascript" >
      var xmlhttp;
      function createXMLHTTPRequest(){
       xmlhttp=false;
         if(window.XMLHttpRequest){//Mozilla浏览器
xmlhttp=new XMLHttpRequest();
if(http_request.overrideMimeType){
xmlhttp.overrideMimeType("text/xml");
}
}
else{
try{
xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}catch(e){}
}
}
}
      function dateRequest()
      {
         var name=document.getElementById ("DropDownList1");
         createXMLHTTPRequest();
         xmlhttp.onreadystatechange=handlestatechange;
         xmlhttp.open("GET","?name="+name.value,true);
         xmlhttp.send(null);
      }
      function handlestatechange()
      {
      
        if(xmlhttp.readystate==4)
        {
          if(xmlhttp.status==200)
          {
              document.getElementById ("mydiv").innerHTML=xmlhttp.ResponseText;
          }
        }
      }
     </script>
</head>
<body>
    <form id="form1" runat ="server" >
  
          <asp:Image ID="Image1" runat="server" ImageUrl="~/images/right3.gif" /><asp:DropDownList
              ID="DropDownList1" runat="server">
          </asp:DropDownList>
     <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
  
      <div id="mydiv">
       </div>
    </form>
   
   
</body>
</html>using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;public partial class requar_deledanwei : System.Web.UI.Page
{
    SqlConnection con;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            this.DropDownList1.Attributes.Add("onchange", "return dateRequest();");
            listdropdown();
            if (name != "")
            {
                getname(name);
            }        }
    }
    public  string name
    {
      
        get
        {
            if (Request ["name"] != null && Request ["name"].ToString ()!= "")
            {
                
                return Request ["name"];            }
            else
            {
                return "";
            }
        }
    }    private void getname(string name)
    {
        string sql = ConfigurationManager.AppSettings["gzgl"];
        con = new SqlConnection(sql);
        con.Open();
        SqlCommand cmd = new SqlCommand("select id,name,code from information where name='"+name+"'", con);
        SqlDataReader sdr = cmd.ExecuteReader();
            string s = @"<table cellspacing='0' cellpadding='4' border='0' id='GridView1'             style='color:#333333;border-collapse:collapse;'>";
        s+="<tr style='color:White;background-color:#990000;font-weight:bold;'>";
        s+="<th scope='col'>流水号</th><th scope='col'>代号</th><th scope='col'>城市</th></tr>";
        int m = 0;
        while (sdr.Read())
        {
            if (m % 2 == 0)
            {
                s += "<tr style='color:#333333;background-color:#FFFBD6;'>";
            }
            else
            {
                s += "<tr style='color:#333333;background-color:White;'>";
            }
            m++;
            s += "<td>" + sdr["id"] + "</td>";
            s += "<td>" + sdr["code"] + "</td>";
            s += "<td>" + sdr["name"] + "</td>";
            s += "</tr>";
        }        
        s+="</table>";
        sdr.Close();
        con.Close();
        this.Response.Write(s);
        Response.End();
    }
    public DataSet getdate(string sql)
    {
        string sqlstr = ConfigurationManager.AppSettings["gzgl"];
        con = new SqlConnection(sqlstr);
        con.Open();
        SqlDataAdapter sda = new SqlDataAdapter(sql, con);
        DataSet ds = new DataSet();
        sda.Fill(ds);
        return ds;
    }
    private void listdropdown()
    {
        string sql = "select * from information";
        DataSet ds = getdate(sql);
        this.DropDownList1.DataSource = ds;
        this.DropDownList1.DataTextField = "name";
        this.DropDownList1.DataValueField = "id";
        this.DropDownList1.DataBind();
    }}