Clear History or Cache (Other post advice dont work)

[StrangerInBeijing]

Why I need to do this:
I got a main page with controls to switch the language (image buttons) and an iFrame where the "body" pages go. When the user switch language, I reload the page, and also the current "body" page.
But if the user click back, it seems it only apply to the main page, not the "body" page and the main page go back to the last language, but not the body page.

So what I want to do is clear the "history" or "cache" if possible. It seems it is, but the advice I found on other post (mostly by M), does not work: Not

System.Web.HttpResponse.RemoveOutputCacheItem("/")

; or

Response.Cache.SetCacheability(HttpCacheability.NoCache);

This code worked on a sample application I wrote, but for some reason not in my "real" website. I loved the "Paged Expired" if u stupid enough to click "back" (Got a " System.Web.HttpException: Response is not available in this context" error..maybe because placed inside an event handler in a form?)

Response.Expires			= 0;
Response.ExpiresAbsolute	= DateTime.Now;
Response.CacheControl		= "no-cache";

You can repliate the problem by following any of the two links to my site in my signature.