The answer here is almost certainly that the purchaser of the ticket(s) in question initiated a chargeback with his or her credit card company. Ticket purchases that were disputed appear in a dark green in your RSVP tab.
What is a chargeback? A chargeback occurs when a ticket purchaser goes to his or her credit card company and “disputes” a charge found on his or billing statement. This is usually: “I did not make this purchase” or “I did not intend to make this purchase.”
Chargebacks are rare, but when they do happen, the money for the ticket is automatically removed from our system, and the ticket is canceled. Find out more about how we handle chargebacks in this article.