Just guessing, but is PatternEntryPropertyWildcard defined inside Assignment? When you write Assignment(null == $shiftType) You are writing a Field Constraint over Assignment. So, the first element of the constraint should be a field from Assignment, but you are putting "null". I think that's your error there. Best, On Sun, May 30, 2010 at 8:50 AM, Geoffrey De Smet <ge0ffrey.spam(a)gmail.com <mailto:ge0ffrey.spam@gmail.com>> wrote: This works in DRL: Assignment( (PatternEntryPropertyWildcard.ANY == $shiftTypeWildcard) || (shiftType == $shiftType) ... ) But this doesn't work in DRL: Assignment( (null == $shiftType) || (shiftType == $shiftType) ... ) It says "no viable alternative at input 'null' in rule" Is there a specific reason why enum literals work on that spot and the null literal doesn't? Here's the full stacktrace: Exception in thread "main" java.lang.IllegalStateException: There are errors in the scoreDrl's:[536,8]: [ERR 101] Line 536:8 no viable alternative at input ')' in rule "unwantedPatternShiftType2DaysPattern" in pattern ShiftType2DaysPattern[542,13]: [ERR 101] Line 542:13 no viable alternative at input 'null' in rule "unwantedPatternShiftType2DaysPattern" in pattern Assignment[544,12]: [ERR 102] Line 544:12 mismatched input '$employee' expecting ')' in rule "unwantedPatternShiftType2DaysPattern" in pattern Assignment[544,32]: [ERR 102] Line 544:32 mismatched input ',' expecting '(' in rule "unwantedPatternShiftType2DaysPattern" in pattern employee[545,8]: [ERR 102] Line 545:8 mismatched input ')' expecting '(' in rule "unwantedPatternShiftType2DaysPattern" in pattern employee in pattern shiftDateDayIndex[547,13]: [ERR 101] Line 547:13 no viable alternative at input 'null' in rule "unwantedPatternShiftType2DaysPattern" in pattern employee in pattern Assignment -- With kind regards, Geoffrey De Smet _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org <mailto:rules-dev@lists.jboss.org> https://lists.jboss.org/mailman/listinfo/rules-dev -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Esteban Aliverti ------------------------------------------------------------------------ _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev