Using EV-30 Exp Pedal to MIDI operate Wah block in Boss GT1000 Core

Hi. I’ve connected & calibrated my EV-30 with an MC6. I can easily turn on and off the Pedal Exp block in my GT1000 Core. What I can’t do is get the Exp pedal to then function properly as a Wah pedal - there is some movement in the pedal position parameters on the GT1000 but they are quite random. I’m also getting the Exp number on the MC6 screen changing from 1 to 2 as I move the EV-30 to toe down. If anyone has done this successfully, can they point me to a set of instructions on how to correctly set this up?