GetMouseButton Not Working

I am trying to make a shoot script. I have done this before in other projects but for some reason it just isn't registering that I am pressing the left mouse button. I recently upgraded to Unity 5 so I am not sure if this is affecting it. Here is my shoot script:`

 var bullet : GameObject;
 
 var isShooting : boolean = false;
 
 function Update () {
     
     if(Input.GetMouseButton(1)) {
         isShooting = true;
         Shoot();
         }
         
     if(Input.GetMouseButtonUp(1)) {
         isShooting = false;
         }
     
 }
 
 function Shoot () {
     
     while(isShooting) {
         Instantiate(bullet, this.transform.position, this.transform.rotation);
         yield WaitForSeconds(0.4);
         }
     
 }