trouble sampling in via ADAT

hello all - i’ve got the adat board in my 4k and im trying to sample in from the roland vp 9000. no problem using coaxial cable but via the adat in i get nothing.

there’s no settings i can find in the MPC to adjust and similar with the VP. have checked both manuals. adat out on the 4k works just fine. sample rates are the same on both machine. any thoughts?

The VP9000 doesn‘t have Adat i/o.
The connectors look identical, but feature optical s/pdif
(same content as the coax)