Volume pedal can't control Aux input level within a registration?

[StuartR]

I've got a secondary keyboard whose sound output I've routed into the Auxiliary inputs of my Genos and I've noticed that its level remains fixed when the volume pedal attached to my Genos is moved. I've got the pedal set to control all parts. Is there any way to change this? I'd rather not have to use another volume pedal on the secondary keyboard.