Actually you should be able to call on Nov 30th. Unfortunately this is completely misunderstood by many, including Disney CM's. My guess is their computer system isn't any better.
According to the
DVC published guidelines, you can call at the 11/7 month mark to the check-out date of the reservation. But, and I'll put this in bold, and quoting directly from my copy of the Guidelines,
"The 'corresponding date' is the date of checkout for the desired reservation; if checkout is to occur on June 25th, then the corresponding date is the 25th. If there are no dates that correspond directly to the reservation checkout date, then the last day of the month is when reservations may be requested.
Since there is no such thing as November 31st, then you may call on November 30th which is the last day of the month.
FWIW, I have never seen anything in print that changes this, and I have sent an e-mail to DVC on two separate occassions requesting clarification, but in both cases received only a notice that someone would be contacting me, but no such contact every came.
My guess is that the people who wrote the policy, and the people who wrote the computer programs, just didn't get together on this one.