2. Extruder doesnt work

Hello i installed the 2. Nozzil on the vertex k8400 printer. I have upload the dual extr. Firmware. Then i wont to load the left filament pla. The nozzil heats but the stepper dont work. For test i have change the extrudersteppers but stepper 1 doesent work to on the stepper 2. Place. So what can i do? Sorry my english is bad

You know the stepper driver for the 2 extruder mounts 180 degrees opposite of the others right?
Try plugging the cables on the motor and control board