FortiAuthenticator Logout for Radius user

Hi,

I had Fortigate setting captive portal with Authentication portal external pointed to FortiAuthenticator. I set radius client on FortiGate and synced it to Fortiauthenticator.   I can access the login page via FortiAuthenticator.  after the login is finished. I force the redirect page to Self-Service Portal on  Fortiauthenticator. When I tried to click the logout button. The page showed "User has successfully logged out from the guest portal. But When I checked on FortiGate's User Monitor. I found the user still alive. Can the fortiAuthenticator force user to log out on FortiGate?

Thank you.