Mine

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ButtonSearchTyped.aspx.cs" Inherits="ButtonSearchTyped" %>

<!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>Untitled Page</title>
    <script runat="server">
    public string SearchString
    {
        get
        {
            return txtSearch.Text;
        }
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label
            id="lblSearch"
            Text="Search:"
            runat="server" />
        <asp:TextBox
            id="txtSearch"
            runat="server" />
        <asp:Button
            id="btnSearch"
            Text="Go!"
            PostBackUrl="ButtonSearchResultsTyped.aspx"
            runat="server" />
    </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;

public partial class ButtonSearchResultsTyped : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Page.PreviousPage != null)
        {
            lblSearch.Text = string.Format("Search For: {0}", PreviousPage.SearchString);
        }
    }
}