Hi, Can I use globals in the LHS of a rule. The rule I have is as follows, package mypackage; import mypackage.Payment; global java.util.Set accountNumbers; rule "Check debtor account number exists" when $p : Payment (accountNumber not memberOf $accountNumbers) then end I insert an instance of HashSet using the setGlobal method on the StatelessKnowledgeSession. However, when I execute the rule, I get the following error. [Error: unable to resolve method: mypackage.Payment.$accountNumbers() [arglength=0]] Kind regards Meeraj