[QUOTE=ISTFlyer;32056860]I don't know what's the problem but it's highly possible that your USA bank(s) are rejecting payment due to security reasons. Possibly the systems think that your intended purchases are scams. Why don't you consider booking a flight via an USA based OTA with a USA card?

I didn't have any problems booking a ticket via the TK website with a Turkish credit card.[/QUOTE

I had the same problem several years ago (and as recently as in January) with trying to book flights on GCC carriers, and their websites. MY Canadian Mastercard said they had absolutely no record of any requests for payment.

Booking and paying through Expedia.ca was no problem and that solved my problem with the GCC carriers.