No sound from MIDI file in Ardour on DrumGizmo track

Question

I am a newbie to Ardour and DrumGizmo. Please be patient.

I followed a tutorial on setting up DrumGizmo. The tutorial shows how to send channels each to a separate bus. I get sound as expected, and that sound is sent to the proper buses, when I click on notes on the keyboard in the piano roll on the DrumGizmo track.
I imported the sample MIDI file from the tutorial. No signal is sent to the buses when I play the track.
I tried a different MIDI file, and tried manually entering notes in the piano roll. Each gives me the same results. No signal to the buses

I am using Ardour 5.12.0 and am running Ubuntu Studio 19.10
Please let me know of other info you need.

What am I missing in setting up a MIDI file?
TIA

Answer 1

Thanks to the folks on the Ardour forum for help with discovering this answer.
In mixer view, on the strip for the channel, I had monitoring set to In. This has to be set to Disk instead.
I am a newbie to Ardour...but, my understanding is that these buttons control what you are monitoring -- In is input to the channel; Disk is what is being read from disk. Seems logical now, after hours of searching.