Since you haven't had any input, I'll try to help. "Master vs slave" probably is not the problem. I don't own either of these keyboards, so I can't tell you step by step how to set them up. But I can try to explain what I think you need to do. . (I did check the Microstation manual).
When using the sequencer in the Microstation (MS), you must record from the MS and save the sequence in the MS. Please consult your manual on setting up the PS60 in this fashion, specifically see what the manual tells you about setting "local off" for the PS60. Also read the sections on how to set-up the midi channels for each keyboard, and the sequencer info for the MS on how to use/control a sound module from the sequencer.
Essentially you need to do your sequencing using the sequencer in the MS, and consider the PS60 as an additional sound module to be controlled from the MS sequencer.
You should be able to configure either keyboard to control the other. But for sequencing and playback from the MS, the MS must "control" the PS60.Once you configure the instruments you should save the configuration information (mid channel, internal/external bank & patch etc) in the sequence.. For replay of the sequence, the instruments must be configured in the same fashion as when recorded.
MIDI does have a learning curve, but it is very useful once you get the hang of it. I find it much easier to sequence/record on a computer than doing it on a workstation. Don