Meaning of "disabling browser caching"

<%
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", -1);
%>

I used this code in a JSP script. I am facing a problem. I navigated from this 
page (say Page 1) to another page (say Page 2).

Then, I tried to use the back button of Page 2 to get back to Page 1. The Page 
1 appeared.

But if this code is meant to disable browser caching, Page 2 shouldn't have 
appeared?

Can anyone tell me exactly what disabling browser caching means?

-------------------------------------------------------------------------
Sponsored by: Watchfire

Methodologies & Tools for Web Application Security Assessment
With the rapid rise in the number and types of security threats, web 
application security assessments should be considered a crucial phase in 
the development of any web application. What methodology should be 
followed? What tools can accelerate the assessment process? 
Download this whitepaper today!

https://www.watchfire.com/securearea/whitepapers.aspx?id=701300000007t9h
--------------------------------------------------------------------------