i can only presume that you did not have the same laser code set up. buddy lasing requires that your lgb is looking for a laser that carries the same code that it is programmed for - in the A10 this means you are setting it up in the weapons screen - not sure on mirage yet.
normally you would also have to set the lgb to autolase for a certain amount of seconds... or lase it manually using the pinky switch - again,,, i am unsure what is modelled int eh mirage yet.