There’s 2 reasons that happens.
1.Banned Players: One of the players that has registered through you has been banned. Once a player gets banned, they have to return all of his or her money to them, and as a result the casino cannot pay Webmasters for revenues generated through banned players.
2.Player Investigation: The casino is investigating information such as credit cards, bank information, or address verification on one of the players brought in by you, and so have withheld payment of profits generated from that player for at least one month.