I couldn't figure out how to get a new audiobook on my new airbag onto my old iPod classic, so I bought a shuffle. When I try to put the book on the shuffle I get "[book] was not copied to the iPod because you are not authorized for it on this computer". So now I have an audiobook sitting on my computer, but can't get it onto either of my iPods. My first choice is to use the classic and return the shuffle, but at this point I'll settle for either one. How do I do this?