Hi nick777
As has already been explained to you in another thread and by affiliates here, your poker player has a negative balance because they have been given a bonus. To be more specific, the player in question has been given a $30 bonus and they have raked $18 so far which leaves the player with a current net revenue balance of -$12.
This player is one of your existing players so the bonus must have been from a loyalty manager as opposed to a sign-on bonus.
Regards
Tim Whyles