Ctrip is the second major travel booking website that has encountered problems with travel agents selling tickets that were redeemed through frequent-flier programs.One day, a man named Fu Jingnan headed to the Haneda airport in Japan, having booked a flight on Ctrip.com, like many of his compatriots.But lo and behold, the airline with which Fu booked the flight refused to give him a boarding pass, saying that his ticket was redeemed by using the mileage points of somebody unrelated to Fu.But when Fu booked the flight on Ctrip, there was no way to find out how these tickets were procured.Indeed, it is a common airline policy to limit customers to using only mileage points accumulated by their own travels or that of their relatives.Ctrip stated that this was a case of travel agents selling tickets redeemed in a dubious way, that it would stop doing business with the travel company in question, and offer compensations to Fu.The episode follows on the heels of another incident where four major airlines cut ties with another popular travel website Qunar over the same issue.In these cases, customers also had no idea where the tickets they purchased on Qunar had come from, and found they had to pay additional fees to make changes to their tickets.Booking platforms like Ctrip and Qunar have deals with other travel agencies so that the latter can sell tickets on the formers’ platforms.But up until now, these platforms have not had the proper screening measures to ensure tickets sold on their platforms were without problem.