The reason why this fails is because you actually have an IsAssignment variable in your task instance (which is null). This because at creation time of the task instance all variables which have read access will be copied from the process instance to the task instance. Since the process instance doesn't have an IsAssignment defined, null will be filled in on task instance level. You can remove the 'read' access or add IsAssignment variable in the process instance. Hope this helps, Olivier. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4084053#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...