The same thing happened to us on our last trip. We were going right after Labor Day 2001 and I figured that it was a slow time of the year, and only called about 30 days in advance (you can book 120 days out). I had a hard time! I got the day that I wanted, but we had to take an early PS (7:45am, I was pregnant and DD was 2 1/2 at the time). So I learned for this trip. I called right at 120 out for 12/4, but we wanted PS for dinner this time.
Keep trying! I always see stories about CRT miracles, so you may get one. If that doesn't work you should call when you get down there. You never know.
I think that this is a fun meal. I have seen a lot of complaints about the food, but we have always had a good meal, and lots of fun!
GOOD LUCK