The Electric Dreams site is goofy, but I finally made it work today. I tried calling them several times and never got an answer, so I have been working on getting their shopping cart to work. If you can't get the cart to keep anything in it after you continue shopping, try signing in before you put anything in the cart. For some reason, they have two kinds of shopping carts, and the one for members works, whereas the one for guests (people who haven't signed in yet), empties itself every time you continue shopping after putting something in the cart.
The bottom line is that I finally got my Carrera axle sets after five days of fooling around.