I think part of your problem might be that ANA flies 2-class 777's on the BKK-NRT route. So, an F award may not show up when only C seats are available on the a/c.

Instead of trying the computer I would call BD's FF phone booking number. They should be able to work things for you or at least definitively tell you one way or the other what availability is. Or they could do a combo award in F/C or on a combo of different airlines. I always have better luck calling (but sometimes more than once) to get my FF bookings.