Reply to Up and down FX to buttons in Traktor Pro

I'm using a nanokontrol for the FX in Traktor pro. I want to map the "FX select" to 2 separate buttons, one to go up the list, and one to go down the list. Is this possible? I can't seem to get it to work. I can only make the list selection go in one direction, so basically all I can get to work is 2 buttons going down the list when I want one to go up and one to go down.

Any help greatly appreciated.