NullReferenceException: Object reference not set to an instance of an object - MonoBehaviour

This is driving me mad as this script should work and makes sense to me, basically where the error is occurring is where I want a MonoBehaviour script to be disabled/false and the other one to be true, here is the first 26 lines of code.

 #pragma strict
 
 //Inspector variables
 
 public var actionOnSpotted : MonoBehaviour;
 public var soundOnSpotted : AudioClip;
 public var actionOnLostSight : MonoBehaviour;
 
 //Private variables
 
 private var player : Transform;
 private var enemy : Transform;
 private var visualArea : boolean = true;
 
 function Awake ()
 
 {
     player = transform;
     enemy = GameObject.FindWithTag("Enemy").transform;
 }
 
 function OnEnable()
 
 {
     actionOnLostSight.enabled = true;
     actionOnSpotted.enabled = false;
 }

Now it is saying the error is on line 26 and saying that it's not referencing anything, but on the Inspector there is a script attached so in theory, this code should be working fine......Or am I missing something?