I gave Phillip your comment, and he will be answering it soon. The likely answer is that you are non-U.S., and as of right now, the cart can't do those (but the programmers are working on it right now, and that will be the next improvement).
I will post Phil's answer soon, but I have a gigantic mini-major auction to finish, and so does Phil (and trust me, it will be worth the wait)!
Bruce