whats wrong with my airplane script

[system]

can anyone tell me whats wrong with my air plane script it dose not move and it dose not shoot it dose nothing if you find an error can you try to correct it and tell me what i did wrong thanks

code:

var throttleSpeed = 30.0;
var turnleftSpeed = 20.0;
var liftSpeed = 20.0;
var desendSpeed = 20.0;
var turnrightSpeed = 20.0;
var misselPrefab: transform;
private var speed : float = 0.0;

function update(){

    if(Input.GetButtonDown("shoot"))
    {   
        var missel = Instantiate(misselPrefab,
                         Gameobject.Find("spawnPoint").transform.position,
                         Quaternion.identity);
    }

    if(GetButton("Lift")) 
    {
        transform.position += transform.forward * liftSpeed * Time.deltaTime;
    }
    if(GetButton("Desend"))
    {
        transform.position += transform.forward * desendSpeed * Time.deltaTime;
    }
    if(GetButton("turnleft")) 
        transform.position += transform.forward * turnleftSpeed * Time.deltaTime;
}

[Loius]

Update, not update.

[system]

did you change the buttons in the project setting you are using in the script like(shoot,lift etc)