Clearing a session in ASP.NET

Question

I'm a new developer, and I've been assigned the task of figuring out why our log out function is not working. I've tried every possible method I can find. Below is the log I've kept that includes the methods I've used.

1. Added a log out button to the CommonHeader.ascx form

2. Have tried numerous methods in the logout.aspx.vb form to get it to end or clear the session but none of them work.

a. ClearSession sub routine defined in the logout.aspx.vb form:

Session("Variable") = ""
FormsAuthentication.SignOut()
Session.RemoveAll()
Session.Abandon()
Session.Clear()

b. Also added this to the top of the Page_Load sub routine:

HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache)
HttpContext.Current.Response.Cache.SetNoServerCaching()
HttpContext.Current.Response.Cache.SetNoStore()

c. Also changed the ClearSession sub routine to Session.Contents.Remove("Variable") from Session("Variable") = ""

None of these methods work. We use Siteminder, and I've been wondering if this is the root of the problem. I just can't find anything on clearing a Session that uses Siteminder. Also keep in mind this application is coded with Visual Studio 2003.

This is the code for the button I'm using in the ascx file:

athp:TopNavText Title="Log Out" NavigateUrl="logout.aspx" Target="_top"/

Then on the "logout.aspx" form I've tried just using one of the methods described above or a combination of each one. This is the code before I ever touch it:

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load  

     ClearSession() 
     Response.Redirect("login.aspx") 

End Sub 

Public Sub ClearSession() 

     Session("Variable") = "" 

End Sub

Answer 1

Finally figured out the solution, I originally did not define the domain upon deletion of the cookie which contained the siteminder session id. The code I used is as following:

        Dim cookie3 As HttpCookie = New HttpCookie("SMSESSION", "NO")
        cookie3.Expires = DateTime.Now.AddYears(-1)
        cookie3.Domain = ".domain.com"
        Response.Cookies.Add(cookie3)

        Response.Redirect("login.aspx")