Hi I have a form, 3 pages in i submit data. On this page I have set no cache

Code:
<% 
    Response.ExpiresAbsolute = DateTime.Now
    Response.Expires = 0
    Response.CacheControl = "no-cache"
    Response.Buffer = True
    Response.Cache.SetCacheability(HttpCacheability.NoCache)
    Response.Cache.SetExpires(DateTime.UtcNow)
    Response.Cache.SetNoStore()
    Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches)
%>


<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="-1">
after successfully submitting I create a session to say user has submitted and redirect to a summary.

Then in page load of submission I check to see this session exists and if so I forward to summary.

Now I submit, go to summary and press back. Submission loads from server and sees session exists and sends to summary. It works fine.

However when I press back again it ignores the submission and goes to the page before.

Can anyone help me with this or at least explain whats happening.

Thanks in advance.