Getting signal from the slave 816c

Hi, I’m hoping someone can help me figure this out, sure its something straight forward, I have 2 ur816c slaved together Ive got the normal 8 tracks showing and the other 8 are ADAT tracks but I can seem to get a signal into cubase from the ADAT tracks, not sure what I’m doing wrong, but I’ve defended into total confusion. I would greatly appreciate and help to shed light on this issue cheers