Just got Ifly for xmas so can really get down to building my 737ng.

MIP finished but now the technical stuff ! Hit a wall !!!!

Got the rotary encoder wired up and calibrated fine, FSCUIP recognizes it, but now i want to use it as the ND screen change switch on the efis until I purchase one from Opencockpits I have FSxpand for the avionics
I have read all the help files but still cant get it to work!

Any help would be appreciated