FPS aiming script doesn't do nothing

I've got this script:

 var animator:Animator;
  
 function Start(){
    animator=GetComponent(Animator);
 }
  
 function Update () {
   if (Input.GetButtonDown ("Fire2") && !animator.GetBool("aimingMode")) {
      animator.SetBool("aimingMode", true);
      aimingMode = true;
   }
   if (Input.GetButtonDown ("Fire2") && animator.GetBool("aimingMode")) {
      animator.SetBool("aimingMode", false);
      aimingMode = false;
   }
 }

In the animator I've got a default state with no animation. Then there is a transition to the aiming state that happens when aimingMode is true. After that I've got a transition (that happens when aimingMode is false) to another state, which has the same animation as the previous state, but with speed -1 so the gun returns to its original position. Finally there is a transition to the first state (the one with no animation) with the exit time condition.

When I only had the first part of the script: var animator:Animator;

 function Start(){
    animator=GetComponent(Animator);
 }
 
 function Update () {
   if (Input.GetButtonDown ("Fire2") && !animator.GetBool("aimingMode")) {
      animator.SetBool("aimingMode", true);
      aimingMode = true;
   }
 }

I tested it and It worked, but now, nothing happens when I press Fire2.