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

Hello Unity Community i have an error everytime i destroy the enemy object within the game:

NullReferenceException: Object reference not set to an instance of an object
Gui track taret.Dead () (at Assets/Scripts/Gui track taret.js:17)
Gui track taret.Update () (at Assets/Scripts/Gui track taret.js:40)

i’v tried almost everything but it doesn’t seem to like calling a function in my quest script, Anyways heres the 2 script:

Gui track taret:

    var Quest1 : Quest1;
    var other : KillSys;
    var HealthBar : Transform;
    private var MaxHealth : float = 100;
    private var MaxBar : float = 0.002;
    var Health = 100;
	var Enemy : GameObject;
	//var DieAnimation : AnimationClip;
  	
  	function Dead()
	{
	//animation.Play("DieAnimation");
		other.KillCounter();	
		Destroy (Enemy);
		Quest1.Kills();
	}   
	
	function Update()
    {
    // --- Change Size Of Bar --- \\
    transform.localScale.z = (MaxBar) * (Health/MaxHealth);
     
    // --- Change Colour Of Bar --- \\
    if(transform.localScale.z == 0.0001)
    {
    transform.renderer.material.color = Color.green;
    }
    if(transform.localScale.z <= 0.0003)
    {
    transform.renderer.material.color = Color.yellow;
    }
    if(transform.localScale.z <= 0.0005)
    {
    transform.renderer.material.color = Color.red;
    }
	if(Health <= 0)
	{
	Dead();
	}
}
function ApplyDammage (TheDammage : int)
{
	Health -= TheDammage;
}

and heres the Quest1 script:

var Killstxt = "Mines Killed: ";
var MaxKills = 5;
static var CurKills = 0;

function OnGUI () {
GUI.Box (Rect (Screen.width*0.9-51, 200, 150, 50), Killstxt + CurKills + " / " + MaxKills);
}

public function Kills(){
CurKills += 1;
}

Oooh! i forgot to assign the “Quest1” in the inspector because of my huge amount of enemy’s… feel so stupid.

Thanks to “KiraSensei” and “jbarba” to solve this out for me ^^