John,
I got a little lost with the flex builder stuff, but from what I can tell you haven't added your service account to the services that you want to print. So lets say you have a Domestic Water map service that you want to print. Your printing service account must have view permissions to that service to be able to print it. I apologize if I am incorrect and you did do this, otherwise I am not to sure what could be wrong.
Good luck!