just gotta keep trying - I went on line for my Oct Bali trip, no flights, then a couple of weeks later suddenly I get both the outbound and return dates I wanted. Mind you that was for Business Class, economy is fully booked even for fare paying passengers (my parents can't get seats).
I think you'll find getting flights to be quite difficult at the moment as there seems to be a surge in demand and not much additional supply of seats - hence asiamiles will get low priority when the airlines can pretty much guarantee a fare paying passenger for you "free" seat instead.
problem with asiamiles is they have been running for years - so many people have them stored up, and there have been so many promotions to get miles from c'cards, restaurants etc.... now actually using them is a different story.