Call them. You do not need to have your TA do that (if you have one), They will stay on the phone with you while you link your ressie. I had to do the same, and in doing so, we discovered that there were many problems with the reservation my TA made.
DCL fixed them for me on the spot. Your problem could be a variety of things including a cookies glitch, turning it off and turning it on again, or mismatched information in the system. Hard to tell until you get on the phone with them. Good luck.