(RADIATOR) User are not able to disconnect

[unixware]

Dear all   i have some problem regarding communication with Radius server and NAS ( Radiaotor 2.18 on Sun Solaris ) using Oracle 9.2.0 ,Cisco AS5300 NAS   i can see correct SessionTimeout is calculated in radius log. but still users are not disconnected and their balance going in negative.   no stop record recieved by Radius .   RAS configuration is seem to be ok.   any help will greatly appreciated   Regards   ./UW