The user didn’t become your referral. The user you invited will become your referral only if he hasn’t been registered in the service earlier. A successful user invitation is accompanied by a service notification. If you invited a user, but there was no notification, then he was a Bitzlato user before your invitation and no referral payments will be made from him.
The user has become your referral. You have received a notification that the user is your referral. Payments from his transactions may not come if the referral doesn’t have enough funds on his wallet to pay the commission for the exchange after the transaction. If there are no funds left on the balance during the trade, the service commission is not debited or part of the amount is debited until the balance is reset.