Can't get particles to enable/disable with button press

I downloaded a basic campfire asset that has light and particle systems to make up the fire, and I want to have the player walk up a press "5" to light the fire. I can get the light element to work but not the empty gameobjects with particle systems!! this is my code (spark, light, and flame are all particle system based):

  var fireLight : GameObject;
 
  var fireSpark : GameObject;
 
  var fireHeat : GameObject;
 
  var fireFlame : GameObject;
 
 
 
  function Start() {
 
      fireLight.SetActive(false);
     fireSpark.gameObject.GetComponent<ParticleSystem>().enableEmission = false;
      fireHeat.gameObject.GetComponent<ParticleSystem>().enableEmission = false;
      fireFlame.gameObject.GetComponent<ParticleSystem>().enableEmission = false;
 
      }
 
  function Update() {
 
     if(Input.GetKeyDown("5"))
     fireLight.SetActive(true);
     fireSpark.gameObject.GetComponent<ParticleSystem>().enableEmission = true;
     fireHeat.gameObject.GetComponent<ParticleSystem>().enableEmission = true; 
     fireFlame.gameObject.GetComponent<ParticleSystem>().enableEmission = true;
 
         }