Are they both connected to the internet and have wireless turned on? It's possible that they detected A9LH on your system and did something to it so you are unable to system transfer to prevent you from downgrading, but I don't think they would do that. If it's a different system, they might've transferred your old system's data to a new one, so you would have to wait a week to transfer again, but there's no way to know. You can't transfer a new 3ds to an old 3ds, so that could be the problem if that's what you're trying to do. That's all I can think of, but you could call them and ask.