Error: 'ASP.webform24_aspx' does not contain a definition for 'btn_announce_Click' and no extension method 'btn_announce_Click' accepting a first argument of type 'ASP.webform24_aspx'

<%@ Page Title="" Language="C#" MasterPageFile="~/Main.master" AutoEventWireup="true" CodeBehind="WebForm24.aspx.cs" Inherits="DXWebApplication1.WebForm24" %>
<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="server">
    <table>
        <tr>
            <td>
                <dx:ASPxButton ID="btn_announce" runat="server" Text="button" OnClick="btn_announce_Click" style="height: 21px"></dx:ASPxButton>
            </td>
        </tr>
        <tr>
            <td>
                <asp:GridView ID="grdvw" runat="server"></asp:GridView>
            </td>
        </tr>
    </table>
</asp:Content>



then

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.OleDb;
using System.Configuration;
namespace DXWebApplication1
{
    public partial class WebForm24 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

       
    }
}


i run this code the error like below occurd help me guys


Server Error in '/' Application.
Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS1061: 'ASP.webform24_aspx' does not contain a definition for 'btn_announce_Click' and no extension method 'btn_announce_Click' accepting a first argument of type 'ASP.webform24_aspx' could be found (are you missing a using directive or an assembly reference?)

Source Error:


Line 4:          <tr>
Line 5:              <td>
Line 6:                  <dx:ASPxButton ID="btn_announce" runat="server" Text="button" OnClick="btn_announce_Click" style="height: 21px"></dx:ASPxButton>
Line 7:              </td>
Line 8:          </tr>