caching problem

I have implemented caching in my application but the page is not cached. My page comes through a load balanced server. The load balance server hits either of the 4 servers that we have and presents the page on the WAP enabled handset. When 0 is pressed from Nokia handset if the page is served through server 2, then browsing from "Go To URL" and typing thee url of server 2, the page remains cached. But when again 0 is pressed the page is served through the server and not from cache........

Pls Suggest?