You shouldn't have to calibrate the Ansibile, I don't think. It's more likely that the Mangrove's volts/octave needs to be calibrated.
When I first got my Ansible and tried MIDI, I had the same problem. I had to switch to the lowest octave that my keyboard could play and then tune my oscillator to a very low note. Then I could octave up through the range and play different notes.
If the lights stay lit the same color/brightness, then something else is wrong - it's more likely then that your MIDI controller is trying to pull too much power (had a similar thing happen with Earthsea but the latest code fixed it).