Are you a travel agent? or own a travel agency? or did you somehow get an IATAN card that you are not entitled to by paying a third party who "sells" them?

You are supposed to book the flight using your own GDS through either the availability display or by doing a long sell (aka direct segment entry).

Depending on the airline, you are supposed to then have their rate desk price it at either their AD75 or AD50 rates.

Once the rate desk prices it, the PNR gets queued back to your GDS so that you can issue the ticket (some airlines may insist on issuing the ticket themselves).

If you don't know what I am talking about, chances are you probably shouldn't even have the IATAN card (as I would assume you are not a legit travel agent) in the first place!! It is meant for people who work full time in the travel industry.

Some airlines may have revenue requirements (eg. you have to sell $X in tickets etc.) before you can book AD travel.