first you need to know if the sensor has been activated :
controller = GameLogic.getCurrentController()
sen = controller.sensors["sensor1"]
if sen.positive :
then retrieve the info :
val = sen.value
be sure val is a string whith no ‘OB’ in its name (use the blender name, not the G.E. name)
if 'OB' in val : val=val[2:]
act = controller.actuators["act"]
act.object = val
act.use3D = True
for track you don’t need to add :
at the end. idem for the sensor, no need to activate the true triggering.
I speak about that because activate is mandatory in most of the other cases.
(it should work but I didn’t test)
have a look here for G.E. API + examples and many more :