[rules-users] error inserting object into working memoery

Why am I getting this error when attempting to insert an object into working memory (stateful session) java.lang.NullPointerException at org.drools.common.DefaultFactHandle.<init>(DefaultFactHandle.java:73) at org.drools.reteoo.ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java:34) at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:57) at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:48) at org.drools.reteoo.FromNode.assertTuple(FromNode.java:86) at org.drools.reteoo.CompositeTupleSinkAdapter.createAndPropagateAssertTuple(CompositeTupleSinkAdapter.java:73) at org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:116) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:317) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153) at org.drools.reteoo.Rete.assertObject(Rete.java:177) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192) at org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:886) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:858) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:659) at com.kronos.webta.service.smarttime.rules.maxiflex.FlowTest.test2(FlowTest.java:168)