[USR-TC] User will not be disconnected when his credit is finished

Hi all, We have a problem with on interaction of TC (with a netserver card) and radius server and that is; when user credit is finished, TC does not disconnect him on that session (Of course user will not be authenticated next time he dials in). Could anybody advise what is the solution? Is it related to SNMP and any special setting?(or MIBs); does it need a Kill Script on radius server? I have this problem with my Windows-based radius server and not with Linux-based radius servers. Thanks for your comments and advises. Kind regards, Shahin