GameObject.Find : why not working?

Hello everyone, maybe it will look like a stupid question to all of you, but until now I only programmed in darkbasic and I’m just starting with Unity, so please, make me understand why this code doesn’t work. I want to have access to an object (child so it moves together) so I can use it’s collision as a trigger. In the code it only rotates with Z because I was trying to see when the access worked, but it didn’t, it continued saying "“NullReferenceException: Object reference not set to an instance of an object
playerBehaviour.Update () (at Assets/Scripts/playerBehaviour.js:44)”
I read and re-read the pages on the other object access and the GameObject.Find(), but I couldn’t understand what I did wrong, neither figure it from the message.
Please help, I’m used to a syntax much simpler, so it may look easy but it isn’t for me.
Code not working:

#pragma strict

public var giocatore : Rigidbody;
private var velocita : float = 1;
private var collinf : GameObject;

function Start () {

giocatore = GetComponent.<Rigidbody>();
collinf = GameObject.Find ("Giocatore/CollisoreInferiore") ;

}

function Update () {
 if ( Input.GetKey (KeyCode.LeftShift) ) {
  velocita = 2;
 }
 else {
  velocita = 1;
 }
 if (Input.GetKeyDown (KeyCode.Space) ) {
  giocatore.velocity = Vector3 (0, 5, 0);
 }
 if ( Input.GetKey (KeyCode.W) ) {
  giocatore.transform.Translate (0, 0, velocita*Time.deltaTime);
 }
 if ( Input.GetKey (KeyCode.S) ) {
  giocatore.transform.Translate (0, 0, -velocita*Time.deltaTime);
 }
 if ( Input.GetKey (KeyCode.D) ) {
  giocatore.transform.Translate (Time.deltaTime, 0, 0);
 }
 if ( Input.GetKey (KeyCode.A) ) {
  giocatore.transform.Translate (-Time.deltaTime, 0, 0);
 }
 if ( Input.GetAxis ("Mouse X") > 0 ) {
 giocatore.transform.Rotate (0, 180*Time.deltaTime, 0);
 }
 if ( Input.GetAxis ("Mouse X") < 0 ) {
 giocatore.transform.Rotate (0, -180*Time.deltaTime, 0);
 }
 
 if ( Input.GetKey (KeyCode.Z) ) {
  collinf.transform.Rotate (0, 0, 180*Time.deltaTime);
 }
 
}

Now it is a child. I tried to use the GameObject.Find in either way: making it a child and separating it (obviously I changed the “Giocatore/CollisoreInferiore” stuff when it wasn’t a child). I made it a child so it moves toghether, I should use it as a proximity trigger in a specific position.
Today I tried to use the find with tag command and it worked perfectly at the first try. This only makes me more confused about why this doesn’t work.

Maybe you should try
collinf = GameObject.Find (“/Giocatore”)
lt’s working for me.
like chinese 玄学