Adding a collider to array

I need to add colliders of the function OnTriggerEnter to the enemiesinrange array, this is my current code:

var enemiesinrange = new Array();
var objects : int = 0; //used to count the enemies in range, not really related.

 function OnTriggerEnter (other : Collider) {
 
 objects++;
 enemiesinrange.Add(Collider);
 print(other.BasicEnemy.age);
 print(enemiesinrange[0].BasicEnemy.age);
 }

Its supposed to add the "other" collider to my enemiesinrange array. It returns an error "Object reference not set to an instance of an object" on the following line:

 **enemiesinrange.Add(Collider);**

Damn, arrays are problematic.