MC8 to EHX Mod Rex Mod Type issue

Hello to everybody, first poster here. I am trying to scroll through the 4 Mod Type options (Vib/Fln/Chr/Phs) on my EHX Mod Rex pedal using an MC8 but having no success.

I have set the pedal to Ch 13, selected Press as the method and used the Midi Dictionary to get the appropriate CC number (18) and Value (3). The CC number tallies with the EHX manual value for Mod Type.

Midi Monitor shows the message being sent but when I pres the allocated footswitch on the MC8 there is no change on my Mod Rex, and the selected mod type does not scroll around or alter no matter what I do.

Has anyone got any suggestions please?