There are many gambling sites that doesn't do negative carryover but accumulates affiliate and increase bonuses and earnings.
The one OP joined is probably an affiliate program with revenue share. Yes, rev shares do have negative carry over or else the casinos profit will go down really bad.
If a casino has a 30% revshare deal with a NC (negative carry over), then the user will share the 30% profit/loss of the user forever. Its like if a referral loses 1 btc bet, the affiliate will get 0.3 BTC and the casino will keep 0.7 BTC. The affiliates have a different "affiliate balance" that calculates all the profit/loss. That is why you will be seeing people negotiating with a casino for a NNC deal (no negative carryover). If the casino does accept the offer, they will be providing it with smaller percentage of commission along with high administrative fee.
On other hand, those over here are saying that they are happy with the 10% of the wager deal, look at it a bit carefully. They provide you 10% of the house edge, not the whole 10% of the wagered amount.