this is a problem with the online system, you should definetely be able to get this room. looking online, it is not available for 7/21-7/23 for points BUT it is available as a paid reservation without any problem for those dates. i had a similar problem booking with points for eilat in august. i just called the spg platinum desk and they took care of it for me, after they had to fool around with the system for a bit. then tell them to try and fix the problem so it doesnt happen for future bookings as well...