I believe there was an error on the system that was double paying BCC payouts on 4 or 5 separate days over the past few months.
If you received a payment on one of those days it was sent twice. When they found the error out, they took the double payments back which left a negative balance you owe back to the pool and until it is paid off you wont get profits since you already got them in advanced some time ago.
More info on this subject can be found here:
https://forums.prohashing.com/viewtopic.php?f=4&t=2347&hilit=overpaid
