It is possible that you are hitting an advance purchase restriction.
Try a consolidator. They often have advance purchase rates without the
date restrictions. FFM

abdul rahim wrote:

suddenly, as of april 1, round-trip fares in May to Athens (from
Dulles) went up from $900 to $1,200!

Will there be another chance at a reasonable fare? I'd thought $900
was too much, but goddamn! $1,200 hurts.