Geeetech

Hi everyone.
I try to turn my Pro B into a dual extruders one.
I've the GT2560 rev A+ board.
I've modify the "configuration.h" and "configuration_adv.h" files this way :

#define EXTRUDERS 2

But, unfortunatly, the E2 motor don't turn. Even in manual mode nor when I print with this extruder.
I've ...