I don't think using a pin code itself will keep you from getting club level, but the availability of the discount on the club level room you wanted might have been used up. I just got a discount pin 2 days ago and immediately started trying to book a stay at the Grand Floridian in standard club level. It took me over half an hour working with the CM to find a series of 4 nights during the discount period where the room we wanted was available.
So my guess is that since your dates probably aren't too flexible, there just wasn't any availability with your pin for the room you wanted during the dates you wanted.
Hope this helps. It is just based on my experience and what I have read from other posts around here.