Instantiate inside class function returns NullReference

Unity is giving me an error Null Reference Exception on this line inside the Fire Function

tempBulPref = GameObject.Instantiate(tempoAmmoPref, fireLocation.transform.position, fireLoc

Everything Works fine until I call the Fire Function

 class Weapon extends Item{
 var range : float;
 var rateOfFire : int;
 var weaponType : weaponType;
 var clipSize : int;
 var fireLocation : Transform;
 var bulletPrefab : ammoType;
 var gWeaponManager : GameObject;
 var tempoAmmoPref : GameObject;
 
 
 function SetValues(){
 gWeaponManager = GameObject.Find("Global Weapons Class Manager");
 Debug.Log(gWeaponManager.name);
 }
 
 function Fire(){
 var tempBulPref : GameObject;
 tempBulPref = GameObject.Instantiate(tempoAmmoPref, fireLocation.transform.position, fireLocation.transform.rotation);
 
 Debug.Log("Shots Fired");
 }
 
 }