Instantiate problem (7012)

[system]

var bullet = GameObject;

function Update () {

    if(Input.GetButtonUp("Jump")){
        var instance : GameObject = Instantiate(bullet, transform.position, transform.rotation);
    }
}

When I use that script I get the following error message:

Assets/launcher.js(6,56): BCE0023: No appropriate version of 'UnityEngine.Object.Instantiate' for the argument list '(System.Type, UnityEngine.Vector3, UnityEngine.Quaternion)' was found.

Any idea what I did wrong. In case you can't tell I'm new to both unity and scripting.

[spinaljack]

change this

var bullet = GameObject;

to this

var bullet : GameObject;

[BlueBottom]

I get the same thing, but my script looks like this:

#pragma strict

var myProjectile = GameObject;
var reloadTime : float = 1f;
var turnSpeed : float = 5f;
var firePauseTime : float = .25f;
var muzzleEffect = GameObject;
var errorAmount : float = .001;
var myTarget : Transform;
var muzzlePositions : Transform;
var turretBall : Transform;

private var nextFireTime : float;
private var nextMoveTime : float;
private var desiredRotation : Quaternion;
private var aimError : float;

function Start () {

}

function Update ()
{
if(myTarget)
{
if(Time.time >= nextMoveTime)
{
CalculateAimPosition(myTarget.position);
turretBall.rotation = Quaternion.Lerp(turretBall.rotation, desiredRotation, Time.deltaTimeturnSpeed);
}
if(Time.time >= nextFireTime)
{
FireProjectile();
}
}
}
function OnTriggerEnter(other : Collider)
{
if(other.gameObject.tag == “Enemy”)
{
nextFireTime = Time.time+(reloadTime0.5);
myTarget = other.gameObject.transform;
}
}
function OnTriggerExit(other : Collider)
{
if(other.gameObject.transform == myTarget)
{
myTarget = null;
}
}
function CalculateAimPosition(targetPos : Vector3)
{
var aimPoint = Vector3(targetPos.x+aimError, targetPos.y+aimError,targetPos.z+aimError);
desiredRotation = Quaternion.LookRotation(aimPoint);
}

function CalculateAimError()
{
aimError = Random.Range(-errorAmount, errorAmount);
}

function FireProjectile()
{
audio.Play();
nextFireTime = Time.time+reloadTime;
nextMoveTime = Time.time+firePauseTime;
CalculateAimError();

for(theMuzzlePos in muzzlePositions)
{
Instantiate (myProjectile, theMuzzlePos.position, theMuzzlePos.rotation);
Instantiate (muzzleEffect, theMuzzlePos.position, theMuzzlePos.rotation);
}
}

can anyone help me with this problem?