Master Page back button

Hi Expert,

There is a Back button in asp.net master page.
 <asp:Button ID="btnBack" runat="server" Text="Back" OnClientClick="history.back(); return false;" />  

It works in one page:
<%@ Page Language="C#" MasterPageFile="~/Dq.master" AutoEventWireup="true" CodeBehind="ReviewPage.aspx.cs" Inherits="ReviewPage" Title="Review Detail" %>

But it does not work in another page:
<%@ Page Language="C#" MasterPageFile="~/MyWeb.master" AutoEventWireup="true" CodeBehind="EmployeeFileDocuments.aspx.cs" Inherits="MyWeb.Reports.EmployeeFileDocuments" Title="Employee Documents Image Report" %>

I am not sure it is the following problem or not:
Inherits="MyWeb.Reports.EmployeeFileDocuments"

Sometimes I got the following error. Appreciated!

Webpage has expired
 
   
 
     
Most likely cause:
•The local copy of this webpage is out of date, and the website requires that you download it again.
 
   
Something to try:
 
   

  Click on the Refresh button on the toolbar to reload the page. After refreshing, you might need to navigate to the specific webpage again, or re-enter information.  
 
   

More information  More information  


If you continue to have this problem, try the following:
1.In Internet Explorer, click the Tools button , click Internet Options, and then click the Advanced tab.
2.Scroll down and clear the “Do not save encrypted pages to disk” option in the Security settings.