Hi, I had been getting that message for the past week when attempting, both by phone and online. I attempted about 30 minutes ago, using my old address, and I was able to order an account transcript, but not a 2015 return transcript. Because I had to enter a Post Office Box, the mistake I made was putting a space between all words (P O Box), but without the space, it allowed me to order (PO Box).
Filed 1/17/16; Accepted 1/19/16