I don,t know shure if this can be resolved easy, but You can try it in the following mode:
First enter in the Rig menu by pressing the Rig button. Now go to the page 3 in the Rig menu and You will see on the Kempers screen the volume pedal settings.
Here You can set You volume pedal to be Post Effects or Pre Effects and go......
I hope this is working for You. 
Hey man! Thanks it works! 
You,re wellcome! 
Dear all!
I am using the old Roland FC200 with my KPA. It is still a great controller, but sending 7Bit Midi. The onboard expression pedal is set to the parameter 7, that as far as I know is standard for volumen. In the KPA this changes the input volumen. I like the control the main output with the pedal. Is this possible with the expression pedal of the FC200 and which setting is needed?
Thx
Hudiluma
How did you get the ctrl foot switch to access tuner? I have an Fc-200 but am still trying to figure out some of the set up. Thanks
Dear all!
I am using the old Roland FC200 with my KPA. It is still a great controller, but sending 7Bit Midi. The onboard expression pedal is set to the parameter 7, that as far as I know is standard for volumen. In the KPA this changes the input volumen. I like the control the main output with the pedal. Is this possible with the expression pedal of the FC200 and which setting is needed?
Thx
Hi Hudiluma,
I'm a beginner too. I have the same FC-200 and I can't figure out how to set this controller so that I can use the pedal for controlling a whammy in the KPA in a song that I have to play for an audition.. It has to do with CC but I haven't a clue how to program that. Can you help me?
