Hi, What is the actual reason for this error? Why cant drools give some better explaination of this problem when the exception is thrown. Here is the snippet of my code: workingMemory.setGlobal("validationErrorHierarchy", validationErrorHierarchy); //workingMemory is StatefulKnowledgeSession I am using the following variable in dslr: *global* com.model.ValidationErrorHierarchy validationErrorHierarchy; thanks saleem _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users