jquery ASP.NET ajax传值问题

大家帮我看看啊 我比较菜
为什么default.aspx页面接受不到值呢？Request.QueryString["name"] 为空Default2.aspx页面
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;  public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        
        string a = Request.QueryString["name"];
        Response.Write("test:"+a);
    }
    
前端：
<!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>
    <title></title>
    <script type="text/javascript" src="js/jquery-1.6.2.min.js"></script>
    <script type="text/javascript">
        $(function () {
            $("#dbtn").click(function () {
                $.ajax({
                    type: "POST",
                    //dataType:"Text",  
                    url: "Default2.aspx",
                    data: { name: "admin", pass: "admin" },
                    beforeSend: function () {
                        $("#ds").html("loading");
                    },
                    success: function (msg) {
                        $("#ds").html("<h1>" + msg + "</h1>");
                    }
                    ,
                    Error: function () {
                        $("#ds").html("<p>" +"ddd"+ "</p>");
                   }
                });            });
        });  
    </script>
</head>
<body>
   <form id="form1" runat="server">  
    <div>  
    <div id="ds"><p>我是AJAX原来的文字！</p></div>  
    <input type="button" value="提交AJAX测试" id="dbtn" name="dbtn" />  
    </div>  
    </form> 
</body>
</html>