When you select PDL on the H9, you are selecting the control source (the expression pedal). You then need to select the destination (a MIDI CC#).
The CC# that the H9 transmits needs to control the parameter on the receiving device, it’s not clear if you have configured the correct CC# to control the parameters of the Nemesis or Ottobit. It looks like CC #4 is the expression pedal value for the Ottobit.
