I don't know whether this is the right place for this question. The Rete Tree view of the Eclipse drl editor does fails for the example drl fild, with "Rete Tree Build Error". I tried the suggestion given in http://www.nabble.com/Problems-with-drools-4.0.7-examples-tp18091849p1809... as well, but does not work. Did any one experienced the same thing ... I have Version: 2.0.0.Beta1-R200810311334 of Jboss Tools on Eclipse, Version: 3.4.1 Build id: M20080911-1700 Stack Trace: java.lang.Exception: Unable to parse rules to show RETE view! at org.drools.eclipse.editors.rete.ReteViewer.loadReteModel(ReteViewer.java:147) at org.drools.eclipse.editors.DRLRuleEditor2$3.run(DRLRuleEditor2.java:244) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121) org.drools.RuntimeDroolsException: Unable to resolve class 'com.sample.DroolsTest$Message' at org.drools.base.ClassFieldAccessorCache.getClass(ClassFieldAccessorCache.java:282) at org.drools.base.ClassFieldAccessorCache.getClassObjectType(ClassFieldAccessorCache.java:206) at org.drools.base.ClassFieldAccessorStore.merge(ClassFieldAccessorStore.java:309) at org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:463) at org.drools.reteoo.ReteooRuleBase.addPackage(ReteooRuleBase.java:381) at org.drools.eclipse.editors.rete.ReteViewer.getRuleBase(ReteViewer.java:115) at org.drools.eclipse.editors.rete.ReteViewer.loadReteModel(ReteViewer.java:145) at org.drools.eclipse.editors.DRLRuleEditor2$3.run(DRLRuleEditor2.java:244) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121) java.lang.reflect.InvocationTargetException at org.drools.eclipse.editors.DRLRuleEditor2$3.run(DRLRuleEditor2.java:251) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121) Caused by: java.lang.Exception: Unable to parse rules to show RETE view! at org.drools.eclipse.editors.rete.ReteViewer.loadReteModel(ReteViewer.java:147) at org.drools.eclipse.editors.DRLRuleEditor2$3.run(DRLRuleEditor2.java:244) ... 1 more Root exception: java.lang.Exception: Unable to parse rules to show RETE view! at org.drools.eclipse.editors.rete.ReteViewer.loadReteModel(ReteViewer.java:147) at org.drools.eclipse.editors.DRLRuleEditor2$3.run(DRLRuleEditor2.java:244) at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)