Keep trying? We got a BOG lunch ADR about 60 days out. We were checking every few days, there was nothing, then all of a sudden there was availability. Supposedly Disney holds back some ADRs and releases them when they feel like it? Try looking on different days of your trip. Try specifying a time instead of just "lunch" or "dinner", I've seen people report getting different results. I've seen people report getting different results on iPad app vs desktop website. If you already have a time, but want earlier, try calling on the phone, I've had experience with phone CM able to add people or change time when nothing available on the app.