This explanation doesn't include sufficient details. What is the name of the airline, and did the airline process the transaction directly? (Does the airline's name appear on your American Express statement?)
If you purchased anything from any airline anywhere in the world you should receive one base point per dollar. If you have a card which earns bonus points for purchasing airfare (such as Premier Rewards Gold) you would earn those bonus points only if the airline's merchant account is setup to match the criteria that American Express uses. This is explain in the terms of the card:
Not only airline name appears on the statement, it has all the ticket details. That rep said I would not receive ANY points (shocking, not even 1 point!) because it was the international airline. I also had two other tickets with AA with all the details, which he also failed to explain why I didn`t get any points.