Reformatted as plain text:Hello All,I have a list of Items that I am inserting into working memory. Here is the rule that is failing: rule "Cannot select X if both Y and Z are not selected" when       Item(code == "X")         (or (not Item(code == "Y"))            (not Item(code == "Z"))) then     System.out.println("Error: You cannot select X unless both Y and Z are selected"); end This rule works correctly when X and Y are there, and when X and Z are there. However, when both Y and Z are missing, the error prints twice. Can anyone tell me what I am doing wrong. Thanks a lot Vithal