Why when i'm making array happend these issues??

#pragma strict
var child : GameObject[];
var size;
function Start () {
child = GameObject.Find ("/HeadCannon");
size = 15;
for(var i : int = 0; i < size; i++)
{
create();
}
}
function create() {
Instantiate (child , transform.position , transform.rotation);
}
function Update () {
}
Cannot convert 'UnityEngine.GameObject' to 'UnityEngine.GameObject[]'

No appropriate version of 'UnityEngine.Object.Instantiate' for the argument list '(UnityEngine.GameObject[], UnityEngine.Vector3,...

Why when i'm making array happend these issues??