[rules-users] Filtering with Null fields ? (Drools 3)

Hello List, In my rules I have something like this : // Locate age group(s) subscriber is categorized within. eval ($f.getCampaign().getAgeRangeGroups() == null || $subscriberAge != null) and AgeRange(lowValue <= $subscriberAge, highValue >= $subscriberAge, ageRangeCode : code) This does not work! What should have been written above is : 1. If Campaign has no AgeRangeGroups() then do not seek AgeRange groups and simply continue to the next constraint, otherwise -> Campaign has age groups, now make sure subscriber is not null and then follow on to find all matching age groups for this subscriber. How can the above be expressed in the drl file? I'm having problems both with the NullPointerExceptions and with the logic not working are requested. Is using null as the default pass condition is wise? If not could you please suggest the correct alternative? Thank you, Maxim. -- Cheers, Maxim Veksler "Free as in Freedom" - Do u GNU ?