final resort

Hello! I need help concerning a problem with my Behringer FCB1010. I'm using a Rocktron Piranha preamp in combination with FCB1010, and I can't get the expression pedals to work ( I've been following directions from the manual, but still, either I'm not competent to make it work, I'm forgeting something or there's something missing in the manual. Please, if someone can help me out, please do. I'd be very grateful... I asked the same thing on some forums, but no one answered unfortunately (( Thanx for listening...