Mauricio,
One more thing I want to tell you I am using Tomcat 6.0 for my development. And configured resource-ref in web.xml and also specifying DB and tranction configuration in context.xml file...
What would be the possible solution and where I am going wrong. I am stucked up with this issue from past 3 weeks. I totally digged into jbpm code as well, however couldn't find the solution..