seems like a lot of people are having the problem. when i tried to send mine, the server was down (probably an overload of people trying to save $84.99).
i'm pretty sure it will be best to take care of this tomorrow when things are cleaned up.
I was having the same problem earlier and they said to try later tonight. I submitted about an hour ago, successfully using a credit card. What kind of card are you using, I think they might only take visa and mastercard?