Sorry for the delay and for the inconvenience. I just checked the calendar, and it looks like September 14th is currently greyed out (not available) for all of the room types. If it was not greyed out when you checked availability previously, it's possible that it was only available as a check-out date. Please note that days shown in lighter blue font are available for check-out, but not for staying overnight or checking in. If the 14th was previously shown in lighter blue font, it means that you could have stayed overnight the 13th and checked out on the 14th, but would not have been able to stay overnight on the 14th. I hope this helps clarify!
Jul 22, 2013