FPS tutorial Spark problems

I have been following the FPS tutorial to the word but when I fire the gun the sparks dont appear when the bullets hit an object they dont show up.

EDIT: Here is the script the gun uses:

 var range = 100.0;
 var fireRate = 0.05;
 var force = 10.0;
 var damage = 5.0;
 var bulletsPerClip = 40;
 var clips = 20;
 var reloadTime = 0.5;
 private var hitParticles : ParticleEmitter;
 var muzzleFlash : Renderer;
 
 private var bulletsLeft : int = 0;
 private var nextFireTime = 0.0;
 private var m_LastFrameShot = -1;
 
 function Start () {
  hitParticles = GetComponentInChildren(ParticleEmitter);
  
  // We don't want to emit particles all the time, only when we hit something.
  if (hitParticles)
  hitParticles.emit = false;
  bulletsLeft = bulletsPerClip;
 }
 
 function LateUpdate() {
  if (muzzleFlash) {
  // We shot this frame, enable the muzzle flash
  if (m_LastFrameShot == Time.frameCount) {
  muzzleFlash.transform.localRotation = Quaternion.AngleAxis(Random.value * 360, Vector3.forward);
  muzzleFlash.enabled = true;
 
  if (audio) {
  if (!audio.isPlaying)
  audio.Play();
  audio.loop = true;
  }
  } else {
  // We didn't, disable the muzzle flash
  muzzleFlash.enabled = false;
  enabled = false;
  
  // Play sound
  if (audio)
  {
  audio.loop = false;
  }
  }
  }
 }
 
 function Fire () {
  if (bulletsLeft == 0)
  return;
  
  // If there is more than one bullet between the last and this frame
  // Reset the nextFireTime
  if (Time.time - fireRate > nextFireTime)
  nextFireTime = Time.time - Time.deltaTime;
  
  // Keep firing until we used up the fire time
  while( nextFireTime < Time.time && bulletsLeft != 0) {
  FireOneShot();
  nextFireTime += fireRate;
  }
 }
 
 function FireOneShot () {
  var direction = transform.TransformDirection(Vector3.forward);
  var hit : RaycastHit;
  
  // Did we hit anything?
  if (Physics.Raycast (transform.position, direction, hit, range)) {
  // Apply a force to the rigidbody we hit
  if (hit.rigidbody)
  hit.rigidbody.AddForceAtPosition(force * direction, hit.point);
  
  // Place the particle system for spawing out of place where we hit the surface!
  // And spawn a couple of particles
  if (hitParticles) {
  hitParticles.transform.position = hit.point;
  hitParticles.transform.rotation = Quaternion.FromToRotation(Vector3.up, hit.normal);
  hitParticles.Emit();
  }
 
  // Send a damage message to the hit object 
  hit.collider.SendMessageUpwards("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
  }
  
  bulletsLeft--;
 
  // Register that we shot this frame,
  // so that the LateUpdate function enabled the muzzleflash renderer for one frame
  m_LastFrameShot = Time.frameCount;
  enabled = true;
  
  // Reload gun in reload Time 
  if (bulletsLeft == 0)
  Reload(); 
 }
 
 function Reload () {
 
  // Wait for reload time first - then add more bullets!
  yield WaitForSeconds(reloadTime);
 
  // We have a clip left reload
  if (clips > 0) {
  clips--;
  bulletsLeft = bulletsPerClip;
  }
 }
 
 function GetBulletsLeft () {
  return bulletsLeft;
 }

And the particles dont even appear in the hierachy when I fire.