I am connecting any instrument in the simplest way possible. Starting the application, Ardour 3.5.7, adding a MIDI track, selecting from the instrument list. The instrument will produce sound from the piano roll view, but not from my LPK25 keyboard. Clicking in the panel which informs me of the disconnection shows me that the MIDI out and in are not connected. Connecting them produces the feedback light. Looking at Qjackqtl shows me that the audio side is connected but no midi connections are made.