Slate SSD4 multi-output?

For the life of me, I can't get a multi-out setup going with SSD4. Have read the instructions, and done what seems obvious … multiple aux's in Pro Tools, then route to out 2 st, out 3 st etc. etc. in the Mixer, with stereo bus 2, stereo bus 3 etc. as inputs to those Aux's.



Not obvious where "out 2 st" is actually going to, but presumably it's my second stereo bus in Pro Tools.



So why am I getting nothing? SSD4 is fine in "default" mode, just comes up my first stereo bus/output.