Passport Logout Problem

We have a passport enabled website , http://www.thespoke.net, and currently our website went live ready, but there are Passport logout problem for a long term, below is the description of the problem:

When the user sign in passport for a period no action there, the passport will be time-out, the return status from Property PassprortIdentity.IsAuthenticated seems correct, return False, but the passport logo tag still showing as [Sign Out], when I manually type in my site’s cookie-delete page that I provided in site passport registration, the passport log tag will be changed to [Sign in]. The expire Cookie Url in Passport registration seems no problem, because When I clicked the [Sign out] button after signed in passport, I can signed out successfully and been redirected to logout page, The only problem seems that the cookie-delete page not been loaded automatically when passport session is time-out.



Any reply or suggestion will be appreciated, thanks very much.