Following rule does not work for me (see exception) - I got the impression that having a calendar for a rule that uses "after" leads to this. Any ideas? (Version 5.5.0 Final)
The point of time I get the exception is NOT within the defined calendar time (the rule should actually be ignored at that time...)

rule "myrule"
calendars "myCalendar"  
when
//an event
$event: Event() from entry-point "EventStream"
//no more events after
  not (Event(this after[0 , 30m] $event)from entry-point "EventStream" )
then
//actions
end

Exception in thread "main" org.drools.RuntimeDroolsException: Unexpected exception executing action org.drools.reteoo.PropagationQueuingNode$PropagateAction@56a75737
at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:995)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:362)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:311)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:127)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:55)
at Application.runSimulation(Test.java:173)
at Application.main(Test.java:68)
Caused by: java.lang.NullPointerException
at org.drools.time.impl.PseudoClockScheduler.removeJob(PseudoClockScheduler.java:147)
at org.drools.common.Scheduler.removeAgendaItem(Scheduler.java:75)
at org.drools.common.DefaultAgenda.removeScheduleItem(DefaultAgenda.java:475)
at org.drools.common.DefaultAgenda.removeActivation(DefaultAgenda.java:352)
at org.drools.common.DefaultAgenda.cancelActivation(DefaultAgenda.java:688)
at org.drools.reteoo.RuleTerminalNode.retractLeftTuple(RuleTerminalNode.java:322)
at org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateRetractLeftTuple(SingleLeftTupleSinkAdapter.java:224)
at org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateRetractLeftTuple(SingleLeftTupleSinkAdapter.java:98)
at org.drools.reteoo.NotNode.retractLeftTuple(NotNode.java:216)
at org.drools.reteoo.CompositeLeftTupleSinkAdapter.doPropagateRetractLeftTuple(CompositeLeftTupleSinkAdapter.java:250)
at org.drools.reteoo.CompositeLeftTupleSinkAdapter.propagateRetractLeftTuple(CompositeLeftTupleSinkAdapter.java:131)
at org.drools.reteoo.NotNode.propagateRetractLeftTuple(NotNode.java:444)
at org.drools.reteoo.NotNode.assertObject(NotNode.java:140)
at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59)
at org.drools.reteoo.PropagationQueuingNode$AssertAction.execute(PropagationQueuingNode.java:426)
at org.drools.reteoo.PropagationQueuingNode.propagateActions(PropagationQueuingNode.java:280)
at org.drools.reteoo.PropagationQueuingNode$PropagateAction.execute(PropagationQueuingNode.java:588)
at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:993)
... 6 more

- Alex