SetEMotor didn't work


Hello there,

i want to controll the conveyor with Python-Api : SetEMotor, like that: dType.SetEMotor(api, 1, 1, 100), but i only heard the motor on conveyor was running , but belt didn’t run. Did anyone know why? I have already changed Library like this:
class EMotor(Structure):
pack = 1
fields = [
(“index”, c_byte),
(“isEnabled”, c_byte),
(“speed”, c_int32)