Internal Error: Invocation Target Exception in funcall of function

Powerloom 4.0.0 beta is giving me an internal error.

Can you tell me if the following error is due to a
Powerloom bug or if I am doing something incorrectly?

When running the following commands:

(deffunction lookup ((?x thing)) :-> (?y function))
(deffunction numVar ((?x thing)) :-> (?y number))
(assert (= (lookup x) numVar))
(assert (=(numVar x)20))
(ask  (forall (?y) (= ((lookup x)x) 20) ) )

I get the following error:

 >> Internal Error: Invocation Target Exception in funcall of function:
     public static edu.isi.powerloom.logic.TruthValue 
edu.isi.powerloom.logic.Logic.askEvaluatorWrapper(edu.isi.stella.Cons) 
(((FORALL (?Y) (= (sk05//NUMVAR @X |L|20) |L|20))))
     java.lang.ArrayIndexOutOfBoundsException: -2147483648
     -2147483648
java.lang.ArrayIndexOutOfBoundsException: -2147483648
     at 
edu.isi.powerloom.logic.PatternVariable.helpBindVariableToValueP(PatternVariable.java:433)
     at 
edu.isi.powerloom.logic.PatternVariable.bindVariableToValueP(PatternVariable.java:401)
     at 
edu.isi.powerloom.logic.ControlFrame.tryUniversalIntroductionProof(ControlFrame.java:1008)
     at 
edu.isi.powerloom.logic.ControlFrame.executeProofStrategy(ControlFrame.java:2502)
     at 
edu.isi.powerloom.logic.ControlFrame.continueCurrentOrNextStrategy(ControlFrame.java:2658)
     at 
edu.isi.powerloom.logic.ControlFrame.continueStrategiesProofs(ControlFrame.java:2776)
     at 
edu.isi.powerloom.logic.ControlFrame.evaluateNextMove(ControlFrame.java:4710)
     at 
edu.isi.powerloom.logic.QueryIterator.executeBackwardChainingProofP(QueryIterator.java:1934)
     at edu.isi.powerloom.logic.QueryIterator.nextP(QueryIterator.java:1402)
     at edu.isi.powerloom.logic.Logic.callAsk(Logic.java:16600)
     at edu.isi.powerloom.logic.Logic.ask(Logic.java:16660)
     at edu.isi.powerloom.logic.Logic.askEvaluatorWrapper(Logic.java:16669)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at edu.isi.stella.javalib.Native.funcall(Native.java:566)
     at edu.isi.stella.Cons.evaluateConsTree(Cons.java:8560)
     at edu.isi.stella.Stella_Object.evaluate(Stella_Object.java:4968)
     at edu.isi.powerloom.logic.Logic.evaluateLogicCommand(Logic.java:31897)
     at edu.isi.powerloom.logic.Logic.logicCommandLoop(Logic.java:31793)
     at edu.isi.powerloom.logic.Logic.powerloom(Logic.java:37844)
     at edu.isi.powerloom.PowerLoom.main(PowerLoom.java:159)
edu.isi.stella.StellaException: Invocation Target Exception in funcall 
of function:
     public static edu.isi.powerloom.logic.TruthValue 
edu.isi.powerloom.logic.Logic.askEvaluatorWrapper(edu.isi.stella.Cons) 
(((FORALL (?Y) (= (sk05//NUMVAR @X |L|20) |L|20))))
     java.lang.ArrayIndexOutOfBoundsException: -2147483648
     -2147483648
java.lang.ArrayIndexOutOfBoundsException: -2147483648
     at 
edu.isi.powerloom.logic.PatternVariable.helpBindVariableToValueP(PatternVariable.java:433)
     at 
edu.isi.powerloom.logic.PatternVariable.bindVariableToValueP(PatternVariable.java:401)
     at 
edu.isi.powerloom.logic.ControlFrame.tryUniversalIntroductionProof(ControlFrame.java:1008)
     at 
edu.isi.powerloom.logic.ControlFrame.executeProofStrategy(ControlFrame.java:2502)
     at 
edu.isi.powerloom.logic.ControlFrame.continueCurrentOrNextStrategy(ControlFrame.java:2658)
     at 
edu.isi.powerloom.logic.ControlFrame.continueStrategiesProofs(ControlFrame.java:2776)
     at 
edu.isi.powerloom.logic.ControlFrame.evaluateNextMove(ControlFrame.java:4710)
     at 
edu.isi.powerloom.logic.QueryIterator.executeBackwardChainingProofP(QueryIterator.java:1934)
     at edu.isi.powerloom.logic.QueryIterator.nextP(QueryIterator.java:1402)
     at edu.isi.powerloom.logic.Logic.callAsk(Logic.java:16600)
     at edu.isi.powerloom.logic.Logic.ask(Logic.java:16660)
     at edu.isi.powerloom.logic.Logic.askEvaluatorWrapper(Logic.java:16669)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at edu.isi.stella.javalib.Native.funcall(Native.java:566)
     at edu.isi.stella.Cons.evaluateConsTree(Cons.java:8560)
     at edu.isi.stella.Stella_Object.evaluate(Stella_Object.java:4968)
     at edu.isi.powerloom.logic.Logic.evaluateLogicCommand(Logic.java:31897)
     at edu.isi.powerloom.logic.Logic.logicCommandLoop(Logic.java:31793)
     at edu.isi.powerloom.logic.Logic.powerloom(Logic.java:37844)
     at edu.isi.powerloom.PowerLoom.main(PowerLoom.java:159)

     at edu.isi.stella.javalib.Native.funcall(Native.java:610)
     at edu.isi.stella.Cons.evaluateConsTree(Cons.java:8560)
     at edu.isi.stella.Stella_Object.evaluate(Stella_Object.java:4968)
     at edu.isi.powerloom.logic.Logic.evaluateLogicCommand(Logic.java:31897)
     at edu.isi.powerloom.logic.Logic.logicCommandLoop(Logic.java:31793)
     at edu.isi.powerloom.logic.Logic.powerloom(Logic.java:37844)
     at edu.isi.powerloom.PowerLoom.main(PowerLoom.java:159)





As always, thanks for your help and time.
Lee Martie