I tried to use it yesterday and it said it had expired on 1/4/13 (even though I was using it on 1/4/13).
Also, in the upper corner of the site it says CHEER$25 but I believe the correct code is CHEERS25 (S instead of $).
I've had a similar thing happen before and when I contacted customer service, they made it right. Edenfantasys.com customer service is really great, in my experience.
You could submit a support ticket (under "HELP" in the top right corner of the homepage) and wait to order until they respond (but you risk having the item/s sell out), or place the order and then open a support ticket.