This can occur due to a correction in the payment of a bet. For example, a bet may have been incorrectly settled as won when it should have been lost.
You may have either withdrawn the paid winnings or played them before the settlement of the bet was corrected. You can rectify your gaming account balance by depositing money into your account.
Please note that even if the payment of winnings is due to an error, customers are not entitled to winnings that were paid out incorrectly, in accordance with the betting rules.
The betting rule applicable to this is A.6.2.