MileKing, yes I have had difficulty on about 50% of my booking attempts. But because I usually request a "saver" award, I accept (grudgingly) that I might have to make consessions as to prefered dates/times, as these have always been "capacity controlled". If it's really important, I just order a "Standard" award which gets me a free seat as long as they still have one to sell. I hate having to use more miles, but hey, that's the difference between Saver and Standard awards on United. I will give United credit though...on at least 2 occasions when I held reservations for a Standard award, I was able to change them to Savers when they released some more Saver seats later on, and got credited for the difference on the mileage .