using Page directive

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" 
AutoEventWireup="true" CodeFile="LoginInformation.aspx.cs" 
Inherits="LoginInformation" Title="Untitled Page" %>

This is the top line of your export.aspx page.
<%@ Page Language="C#" CodeFile="Export.aspx.cs" 
Inherits="Health_Export" %>
--------------------------------------...
this is the class Health_Export in your code behind which 
your aspx page is inheriting.
public partial class Health_Export : System.Web.UI.Page

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

ya this is the correct answer in aspx page we are we are
defined d codefile naaa

<%@ Page Language="C#" AutoEventWireup="false"
CodeFile="dd.aspx.cs" Inherits="ddsolved" %>