[rules-users] Rule exception

[Delaunay Gaetan]

Hi all,
I've got problem with the following rule

rule 'Satellite mediation'
when
PricingField(name=="srv", eval(strValue.contains("VOIX")))
$field : PricingField( name == "duree")
then
mediationManager.addLine(11,$field.getIntValue());
end

I've got this exception when this rule is use
java.lang.AbstractMethodError: 
Mediation.Rule_Satellite_mediation_0ReturnValue0Invoker.evaluate(Ljava/lang/Object;Lorg/drools/spi/Tuple;[Lorg/drools/rule/Declaration;[Lorg/drools/rule/Declaration;Lorg/drools/WorkingMemory;)Z
    at 
org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:210)
    at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:132)
    at 
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:317)
    at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:140)
    at 
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:298)
    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)

What's wrong?