BMW Repair: charging system, amp alternator, charging system

Question
ok brand new starter, brand new 120 amp alternator and brand new battery.  The alternator is not charging the battery.  I have checked everything and can not find a smoking gun.  HELP!!

Answer
Well first I needed to know what it was for a car.You might want to see if the light on the instrument cluster is working.When you turn your key to the on postion does it illuminate.If not you need to replace the bulb ,as it completes the charging circuit.