I'll have to admit, I was a bit nervous because the font used on the code number leaves a lot of ambiguity between, say, an 'A' and an 'R,' an 'O' and a '0.' I just plowed ahead and entered what I thought my code to be, and lo and behold the -$20 discount came right up.
I would suggest you check your membership number to see if any of the letters/numbers might be misconstrued.
Chris in NH