Upgrade availability VS65 12/3/11

The better half & I are flying out to MBJ in PE. We've already upgraded the return leg to UC, but I'm thinking about upgrading the outbound too.

The only problem is availability...there'e no option available on the booking details on the VS website & ExpertFlyer shows all UC buckets as 0. This seems a litle odd as all of the flights between LGW & MBJ during that same couple of weeks still have good availability. Is something likely to be "corrected" with this flight or is there something so popular about flying to MBJ on 12/3/11 that I don't know about!!!

Given the rest of the flight is wide open, could be a group booking already in place? Or maybe this aircraft doesn't have an Upper Class section...!

From what I can see Upper Class is full on this flight, but there are only 14 seats available anyway.