Funnily enough, I tried this yesterday, giving the codes and ticket names provided by yourselves.
First, on the train to Leeds. The guard attempted to put the code in but could get no joy on the ticket.
Second time I tried at Leeds station, but even though the code showed up (the lady in the booking office even turned the screen round to show me), there wasn't a way to print it out. The consensus seemed to be that it needed its own ticket stock.
Thirdly, I tried on the train which was going to Manchester, and the guard again said he couldn't print it out because it needed its own ticket stock. He suggested I brought it from a station in Manchester.
It seems a bit silly that I was unable to buy the said ticket. What do people do if the ticket office in one of the Manchester stations is closed?