[rules-users] How to accumulate from objects in a collection?

Hi, this is just a dumb question for drools-languaje gurus... like Edson :) How ca I write a rule (CE in LHS) for accumulate atributes inside an object, but this objects are not facts, they are inside a collection which is an attribute from a fact... pretty messy right?...lol.. well, the business problem is this. I need to count (accumulate) vacation days used on previous vacation requests. I have an User (which is one fact) having a collection of oldVacationRequests and an actual VacationRequest (the another fact). So the rules is like this: discount to the available days for vacation those used in previous vacation request, and those days are the days between initDate and endDate in each old vacation request with isAproved seted true and having endDate before the actual vacation request initDate. did I explain myself?... so I need to know if this is possible I was trying to do something like this...but is obviously wrong...:) rule "remove used vacation days" no-loop when vr: VacationRequestVO($days: availableDays , $iniDate: initDate ) $u: UserVO( $vacReqList: vacationRequestList ) $usedDays: Number (intValue > 1) from accumulate ( $ovr: VacationRequestVO( isAproved == true, endDate < $iniDate, $uDays: usedDays), from $vacReqList, count($uDays)) then vr.setAvailableDays($days - $usedDays); end Thanks... Felipe Piccolini M. felipe.piccolini(a)bluesoft.cl