Yeah, your dates aren't on the list right now. If you call the hotel directly, you can book the 15% discount rate if you have an entertainment card or if you simply mention the DisBoards. If you have a Disney AP, you can get 20% off for your dates. The online code for Disney AP 20% off rate is LNAP.
For future reference, if all your dates are available on the retro rate, the code for using your Entertainment card is LKEP and for your AP is LKAP. They don't always work though even if the dates are available, so it might be better to call directly. Also, if you want to make a reservation for which some of your dates get the retro discount and some a lesser discount, you need to call and do that with a person; the online booking doesn't seem to handle that. Only speak to in-house reservations; the national line will not book these special discount rates.