bullet hole problem/raycast problem || help me please

hi every one. For my fps "minigame", for my bullet hole, I use a script (watch down).

 #pragma strict
 var timer=3;
 var bulletHole: GameObject;
 var force=200;
 
 
 function Start () 
 {
     yield WaitForSeconds(timer);
     Destroy(gameObject);
 }
 
 function OnCollisionEnter()
 {
     Destroy(gameObject);
 }
 
 function Update()
 {
     var hit : RaycastHit;
     var direction=transform.TransformDirection(Vector3.forward);
     
     if(Physics.Raycast(transform.position,direction,hit,5))
     {
     var tempRot=Quaternion.FromToRotation(Vector3.up,hit.normal);
     var holesBull=Instantiate(bulletHole,hit.point,tempRot);
     }
 }

I instance my bullet with a force, and in the bullet prefab there is the script, in the script THERE IS the componente gameObject bulletHole.

when I start the game, the script work perfectly, with the bullet hole and more, BUT, I have this error in the console :

The variable foroSparo of proiettile has not been assigned. You probably need to assign the foroSparo variable of the proiettile script in the inspector.

I don't now why, becose in the prefab, there is the script with the gameObject reference.

Can you help me please?