midi mapping Windows version on pioneer ddj rb

Hi, I want to MIDI map pre listening (headphone que ́s) manually for Pioneer DDJ-RB, Windows version. I connect Control: note C6, targeting: mixer, action: Deck 1 active monitor and Deck 2 active monitor. I want to use external mode. The buttons will not work. Can anybody tell me why? And help me how to solve this?

Thank you for your help!