[Users] radius accounting problem

hi all, reading acc modules README: * There is no session accounting -- OpenSER maintains no sessions. If one needs to correlate INVITEs with BYEs for example for purpose of billing, then it is better done in the entity which collects accounting information. Otherwise, SIP server would have to become sessions-stateful, which would very badly impact its scalability. so it's impossible to do radius accounting for billing purpose? i need a B2BUA for that? any hints? anyway i'm trying radius acct this is my problem: 0(25586) ACC: transaction answered: call_id=d3cd352603256e75@ua1, totag=360701152, from="222" <sip:222@mysip>;tag=d288f8fc7ea68a04, i-uri=sip:111@ss:5060, method=BYE, o-uri=sip:111@ss:5060, fromtag=d288f8fc7ea68a04, code=200, to=<sip:111@mysip>;tag=360701152, uid=n/a, userpart=111 0(25586) ERROR: acc_rad_request: radius-ing failed i've activated all possible debug but i received only this message about radius. i'm trying to activate debug for radiusclient this is my setup: FreeBSD 6.1 OpenSER 1.0.1 radiusclient-0.5.2 thank you