Keep trying. If you are determined to get it, try at least twice a day online.
I wanted CR MK-view for my trip in January. It showed up online somewhere around final payment time. I hemmed and hawwed and finally called an hour later to switch over. Nope...gone.
Three days later, it popped up again. I called CRO and by the time I got to an agent it was gone again.
A week or so later, I caught it just right and got my room with the 4/3 deal. I checked after I booked and it still showed up. It stayed online for probably 2-3 days and is now gone again.
Oh, and this wasn't just for the CR. The same thing was happening with a majority of the deluxes. At one point, I couldn't get anything above WL or AKL. Eventually I had my choice of any deluxe resort.