[rules-users] Views???

Hi, I 'm new to drools and want to see how the views work(The Agenda View,The Working Memory View,...). I have created a rule project and a break point at workingMemory.fireAllRules() line in sample class and debugged it as drools application. After I have selected the working memory variable as explained in the documentation and opened the Agenda View or the other views, I got this message: java.lang.NoClassDefFoundError: org/eclipse/debug/internal/ui/contexts/provisional/IDebugContextListener at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:620) .... How can I use this views?Did I do something wrong or maybe forget any thing? thanks in advanced. M.A