I booked 3 meals at ala carte restaurants, then tried to book Teppanyaki. I also only had two meals on the SDP and was going to purchase the other two later. This must be the problem.
I may be able to get this right if I first buy SDP for the extra meals, or as you suggest, cancel the others and book Teppanyaki first. Since I'm less than 30 days out from departure, I'm not sure I want to try that.
Could they make this any more complicated?!!