GetButton problem

i got this script to instantiate and destroy objects when a certain button is pressed, but somehow it won't work, it's not giving me errors, so i can't figure out what's wrong.. Here's the script:

var currentObject : Transform;

var idle : Transform;
var walk : Transform;
var run : Transform;
var jump : Transform;
var fight : Transform;

function Update ()
{
    var currentPosition;
    currentPosition  = transform.TransformPoint(Vector3.zero); 
}
//function Start () 
//{
//  var obj = Instantiate(idle, transform.position, transform.rotation);
//  obj.transform.parent=transform;
//}

if (Input.GetButton("Jump")) 
{
    //Destroy(idle.gameObject);
    var obj = Instantiate(jump, transform.position, transform.rotation);
    obj.transform.parent=transform;
}

Try adding it to the update function