Hi, I am trying to use RCP to develop a BRMS. But I am a newcomer of both RCP and DRools. The problem in my program is: A view can not be displayed properly while the DRools program is added in my RCP project. But if I disable below statement, the view can be displayed: workingMemory = ruleBase.newStatefulSession(); Error message and a view RCP codes in which rule is fired are attached. My steps of constructing the RCP+DRools project: 1. Create Plug-in project with RCP 2. Add customized view and add some buttons 3. Run as Eclipse Application, everything is fine 4. "Convert to DRools project" using the pop-up menu, some DRools libraries were added. 5. Add button event and fire rules in a view - "EditView" 6. Run as Eclipse Application, EditView can not be displayed properly and throw out error message. 7. if "workingMemory = ruleBase.newStatefulSession();" is disabled, the view can be display correctly again. Is my DRools calling method in RCP correct? Please comment. Thanks, David