5103 recording digital music

Hi just ran into a problem with my 5103 preamp. Have a digital bitstream going into Dig 1, plays music fine but wanted to setup a record path to one of the analogue record outs. Doesn't seem to let me - "no outputs available" or some such message. However I can record from an analogue input through the same out no problem.
Is this something to do with the analogue and digital inputs being completely separated internally or something I am not doing correctly in the setup?

Cheers
Andy