That only happens if a jobset is empty.
Have you changed something in your config.xml by hand? If not, I'd be happy if you could try to reproduce this problem.
i definitely have not edited anything by hand.
Edit: The problem is sitting here. But i presume you want me to find a way to make the problem stop happening, then start happening again?
By the way, what you are looking for is an event listener. However, you could tell us what you're trying to do and maybe there is a way it can be done with the scheduler.
i wanted to update TunnelBroker when i get a new IPv4 address.