Controll a SD40 by using the Boss FS-6 foot switch - trouble

[Thomsky]

Dear people,

I want to control the Ketron SD40 with a Boss FS6 foot switch but I can't get it to work. I followed the manual but for some reason the SD40 doesn't react to the FS6. The FS-6 is working. I checked that with another piece of hardware.
I hope someone can enlighten me....
What I plan to do is switching in between two different voices. E.g. switch A on the FS6 activates a bass voice and switch B changes to a bass. I hope someone can guide me to get it work. I have sent an email to the Ketron support. Still no reply until today....
I will be happy to get any hints/advices about how to solves this...
Cheers, Thomsky