End or Remove a session

This question has been asked a great number of time, however, the suggestions I have found don't work for me.

I have a Master page with a hyperlink pointing to a logout.aspx page. In the prerender of the logout page I have the following:

FormsAuthentication.SignOut()

Session.Abandon()

Session.Clear()

Even after the user clicks the link and is redirected to the logout page. If I login as an administrator and check my membership list of users it still shows the user logged in.

Any help on this is very appreciated.
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