Force Page Expiry (Back Button Issue)

[jaydfischer]

Here is the code that I tried with no luck. Even though the cache is
not saved, the page still appears but goes to the server to get the
page instead of local cache. When it comes back to the page load event
the ViewState no longer exist but the session does.

Any help would be greatly appreciated!
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArg s) Handles MyBase.Load
If Not IsPostBack Then

If IsExpired() Then
Response.Redire ct("expired.asp x")
Else
Me.SaveTimeStam ps()
End If
Response.Cache. SetCacheability (HttpCacheabili ty.NoCache)
Response.Cache. SetExpires(Now( ).AddSeconds(-1))
Response.Cache. SetNoStore()
Response.AddHea der("Pragma", "no-cache")
End If
End Sub

Private Sub LinkButton1_Cli ck(ByVal sender As System.Object, ByVal
e As System.EventArg s)

End Sub
Private Sub SaveTimeStamps( )
Dim t As DateTime = Now
ViewState.Add(" TimeStamp", t)
Session.Add("Ti meStamp", t)
End Sub
Private Function IsExpired() As Boolean
If Session("TimeSt amp") Is Nothing Then
Return False
ElseIf ViewState("Time Stamp") Is Nothing Then
Return False
ElseIf ViewState("Time Stamp").ToStrin g =
Session("TimeSt amp").ToString Then
Return False
Else
Return True
End If
End Function

Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click
Response.Redire ct("webform2.as px")
End Sub
End Class