You will need to be more specific about what you mean by "it's not working" for anybody to be able to help you. What are you expecting to see and what happens? Are there any stacktraces printed to the console? If so, please attach them.
P.s. I'm forwarding this message to the user group which is better suited for this type of question than the dev list you sent the message to initially which is for questions about Geb development and not usage questions. Please reply to the user group.