northam,
I think I know what the problem is, and it's with my relationship with TDA. I opened a bare minimum account there so that I can have access to all their software. But I don't use them for trading because I hate navigating their behemoth menu system and using their poor documentation. I prefer ETrade for trading because the executions are speedy (always less than 2 seconds), have perfect pricing, and the commissions are lower.
I think that the problem is that I not only had to open a minimum account but that I also have to maintain that minimum amount. When I set up the account, the rules seemed to say that I needed a minimum amount to open the account but nothing was said indicating that I had to maintain that level beyond a minimal grace period. So I'll test that idea by electronically transferring a few hundred bucks over to TDA and see what happens overnight after they balance their books.
