Problems with Mainstage triggering synth mod.

I use the music player within Mainstage to play along with backing tracks. However, every time I press the 'Play' button in Mainstage, as well as start the relevant audio track, it also activates the start button on my recently-purchased Roland JD-08 synth module, causing it to randomly generate notes. Mainstage is obviously generating a midi signal in order to trigger my Roland, but I do not know how to view the signal. If I could see it, I would hopefully be able to to stop it happening. Please note that I have unticked all of the checkboxes in the MIDI tab of the concert settings, which made no difference. I am also using a MiniMac with the latest OS update.

If I fire up Midiview, it lists all of my MIDI instruments but not Mainstage. I have also downloaded MIDIpipe but again, it will not allow me to view Mainstage.

So, my question is...does anyone know of a way to view the MIDI signals being sent out from Mainstage?

Thanks.

[Edited by Moderator]