Why is this player script not working

OK, it seems there is ALWAYS something wrong. I get an error message at line 19,31 but it looks straight forward enough to me, it follows along with the rest of the weapons attacked to my FPS main camera so I can't figure out why i'm getting this error??

Here is my Script:

var maximumHitPoints = 100.0;
var hitPoints = 100.0;

var grenadesGUI : GUIText;
var bulletGUI : GUIText;
var shotgunGUI : GUIText;
var rocketGUI : DrawRockets;
var healthGUI : GUITexture;

var walkSounds : AudioClip[];
var painLittle : AudioClip;
var painBig : AudioClip;
var die : AudioClip;
var audioStepLength = 0.3;

private var machineGun : MachineGun;
private var shotgun : Shotgun;
private var rocketLauncher : RocketLauncher;
private var grenadeLauncher : GrenadeLauncher;
private var healthGUIWidth = 0.0;
private var gotHitTimer = -1.0;

var rocketTextures : Texture[];

function Awake () {
    shotgun = GetComponentInChildren(Shotgun);
    machineGun = GetComponentInChildren(MachineGun);
    rocketLauncher = GetComponentInChildren(RocketLauncher);
    grenadeLauncher = GetComponentInChildren(GrenadeLauncher);

    PlayStepSounds();

    healthGUIWidth = healthGUI.pixelInset.width;
}

function ApplyDamage (damage : float) {
    if (hitPoints < 0.0)
        return;

    // Apply damage
    hitPoints -= damage;

    // Play pain sound when getting hit - but don't play so often
    if (Time.time > gotHitTimer && painBig && painLittle) {
        // Play a big pain sound
        if (hitPoints < maximumHitPoints * 0.2 || damage > 20) {
            audio.PlayOneShot(painBig, 1.0 / audio.volume);
            gotHitTimer = Time.time + Random.Range(painBig.length * 2, painBig.length * 3);
        } else {
            // Play a small pain sound
            audio.PlayOneShot(painLittle, 1.0 / audio.volume);
            gotHitTimer = Time.time + Random.Range(painLittle.length * 2, painLittle.length * 3);
        }
    }

    // Are we dead?
    if (hitPoints < 0.0)
        Die();
}

function Die () {
    if (die)
        AudioSource.PlayClipAtPoint(die, transform.position);

    // Disable all script behaviours (Essentially deactivating player control)
    var coms : Component[] = GetComponentsInChildren(MonoBehaviour);
    for (var b in coms) {
        var p : MonoBehaviour = b as MonoBehaviour;
        if (p)
            p.enabled = false;
    }

    LevelLoadFade.FadeAndLoadLevel(Application.loadedLevel, Color.white, 2.0);
}

function LateUpdate () {
    // Update gui every frame
    // We do this in late update to make sure machine guns etc. were already executed
    UpdateGUI();
}

function PlayStepSounds () {
    var controller : CharacterController = GetComponent(CharacterController);

    while (true) {
        if (controller.isGrounded && controller.velocity.magnitude > 0.3) {
            audio.clip = walkSounds[Random.Range(0, walkSounds.length)];
            audio.Play();
            yield WaitForSeconds(audioStepLength);
        } else {
            yield;
        }
    }
}

function UpdateGUI () {
    // Update health gui
    // The health gui is rendered using a overlay texture which is scaled down based on health
    // - Calculate fraction of how much health we have left (0...1)
    var healthFraction = Mathf.Clamp01(hitPoints / maximumHitPoints);

    // - Adjust maximum pixel inset based on it
    healthGUI.pixelInset.xMax = healthGUI.pixelInset.xMin + healthGUIWidth * healthFraction;

    // Update machine gun gui
    // Machine gun gui is simply drawn with a bullet counter text
    if (machineGun) {
        bulletGUI.text = machineGun.GetBulletsLeft().ToString();
    }

    // Update Shotgun gui
    // Shotgun gui is simply drawn with a bullet counter text
    if (shotgun) {
        shotgunGUI.text = shotgun.GetBulletsLeft().ToString();
    }

    // Update Grenade Launcher gui
    // Grenade Launcher gui is simply drawn with a bullet counter text
    if (grenadeLauncher) {
        grenadesGUI.text = grenadeLauncher.GetBulletsLeft().ToString();
    }

    // Update rocket gui
    // This is changed from the tutorial PDF. You need to assign the 20 Rocket textures found in the GUI/Rockets folder
    // to the RocketTextures property.
    if (rocketLauncher) {
        rocketGUI.UpdateRockets(rocketLauncher.ammoCount);
        /*if (rocketTextures.Length == 0) {
            Debug.LogError ("The tutorial was changed with Unity 2.0 - You need to assign the 20 Rocket textures found in the GUI/Rockets folder to the RocketTextures property.");
        } else {
            rocketGUI.texture = rocketTextures[rocketLauncher.ammoCount];
        }*/
    }
}

EDIT: this is the error message I get Assets/WeaponScripts/FPSPlayer.js(121,52): BCE0019: 'GetBulletsLeft' is not a member of 'MissileLauncher'.

I should also mention that I changed my Grenade Launcher to "Missile Launcher" since I thought maybe it was calling on that script. I noticed the scripts attached to all of the other weapons had the same name so just to be consistant I changed the name to match... lol it didn't help though :(

Here is my Missile Launcher Script:

var projectile : Rigidbody;
var initialSpeed = 20.0;
var reloadTime = 0.6;
var ammoCount = 20;
private var lastShot = -10.0;
function Fire ()
{
// Did the time exceed the reload time?
if (Time.time > reloadTime + lastShot && ammoCount > 0)
{
// create a new projectile, use the same position and rotation as the Launcher.
var instantiatedProjectile : Rigidbody = Instantiate (projectile,
transform.position, transform.rotation);
// Give it an initial forward velocity. The direction is along the z-axis of
// the missile launcher's transform.
instantiatedProjectile.velocity = transform.TransformDirection(
Vector3 (0, 0, initialSpeed));
// Ignore collisions between the missile and the character controller
Physics.IgnoreCollision(instantiatedProjectile.collider, transform.root.collider);
lastShot = Time.time;
ammoCount--;
}
}

GetBulletsLeft() is indeed not a function in your MissileLauncher script. I don't know how your other weapons scripts look, but they either have such a function, or are subclassed from a class that has it. I'd then look at the other scripts to see how they define GetBulletsLeft and add that to your missile launcher script, or something along that line. Or subclass missile launcher from whatever your other weapons subclass from (if anything).