[/quote] Well, the actual MIDI mesaages sent on the Switch Doctor are 0-127 even though they’re displayed as 1-128. Does that mean that if the expression value on the H9 is set at MIDI CC2 it needs to be set as MIDI CC2 on the Switch Doctor?[/quote]

If the Switch Doctor is supposed to be sending on CC2 and the H9 isn't reacting to it when you set its expression pedal CC2, then I'd try setting the H9 to CC1 or CC3 to see if you get something there.

There's also a learn mode on the H9 itself as it mentions on page 37 of the manual, but to use that, you'll have to get into the H9s system mode:

https://s3.amazonaws.com/com.eventide.downloads/Product+Manuals/H9-UserGuide.pdf