为什么传递内容不变

我用了一个droplist想根据这个里面的内容打开页面，可是不管我选哪个，里面的内容总是原来那个  <%@ Page Language="C#"%>
<%@ Import Namespace="System.Data.OleDb"%><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    void Page_Load(Object sender, EventArgs e)
    {
        OleDbConnection condatabase;
        OleDbCommand cmdSelectdatabase;
        OleDbDataReader dtrdatabase;
        // Retrieve records from database
        condatabase = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA Source=E:\\powerflow\\loadflow.mdb");
        condatabase.Open();
        cmdSelectdatabase = new OleDbCommand("Select * from main ", condatabase);
        dtrdatabase = cmdSelectdatabase.ExecuteReader();        // Bind to dropdownlist
        droplist.DataSource = dtrdatabase;
        droplist.DataTextField = "TYPE";
        droplist.DataBind();
        dtrdatabase.Close();
        condatabase.Close();
    }
    void Search_Click(object sender, System.EventArgs e)
    {
        OleDbConnection condatabase;
        string strSelect;
        OleDbCommand cmdSelect;        condatabase = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA Source=E:\\powerflow\\loadflow.mdb");
        strSelect = "Select SIGN From main Where TYPE=@type ";
        cmdSelect = new OleDbCommand(strSelect, condatabase);        cmdSelect.Parameters.Add("@type", droplist.SelectedValue);
        condatabase.Open();
        
        if ((int)cmdSelect.ExecuteScalar()!=0)
        {
            Response.Redirect("node1.aspx?rr=" + droplist.SelectedValue);
        }
        else
        {
            Response.Redirect("Branch.aspx?rr="+droplist.SelectedValue);
        }
        condatabase.Close();
    }
    
    </script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server" >
    <div>
    <asp:DropDownList
  ID="droplist"
  Runat="Server" />
<asp:Button ID="Button1"
  Text="查询" 
  Runat="Server" OnClick="Search_Click"/>    </div>
    </form>
</body>
</html>