Change device parameter +/- 1 with buttons not knobs

I'm trying to change the first parameter of the first device of the selected track with buttons and not knobs for a specific purpose of navigating through the chain selector macro (which results in which instrument is played in that track).

One button should increase the "knob" of the chain selector + 1 the other button should decrease it - 1.

I did this setup:
https://i.imgur.com/jngDwKp.jpg

This seems right to me however the decrease button only puts it on 0 (does not decrease by 1 but always puts it to 0) while the increase button doesn't seem to do anything.

How can I fix this? Seems hard to control a device parameter with buttons instead of knobs or faders.