use this code it might help you to fix your Problem..
the .aspx page
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ajax.aspx.cs" Inherits="ajax" %>
<!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>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:Timer ID="Timer1" runat="server">
</asp:Timer>
<table>
<tr>
<td>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
<tr>
<td>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
<tr>
<td> <asp:Button ID="Button1" runat="server" Text="Button1"
onclick="Button1_Click" /> </td>
<td> <asp:Button ID="Button2" runat="server" Text="Button2" onclick="Button2_Click" /> </td>
</tr>
</table>
</form>
</body>
</html>
the aspx.cs file
using System;
using System.Threading;
public partial class ajax : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
TextBox1.Text = "Ajax Clicked";
Thread.Sleep(1000);
}
protected void Button2_Click(object sender, EventArgs e)
{
TextBox2.Text = "Ajax Asynchrnously clicked";
}
}
I hope this will helps you