How can I increase the value of a variable?

Hi, I am trying to make a quicktime event thing when I enter a trigger the E key pops up, and you must press the E key 30 times and then a animation will play. How can I accomplish this? I’ve tried, but it didn’t work. The variable Presses dosen’t want to increase.

Here’s my script:

var Ekey : GUITexture;
var Cube : GameObject;
var Presses = 00.0;
var MaxPresses = 30.0;





function OnTriggerEnter () {
  Ekey.enabled = true;
 if(Input.GetButtonDown("E")){
 
     if(Presses < MaxPresses){
   Ekey.animation.Play();
   Presses += 1;
   
   if(Presses > MaxPresses){
    Ekey.enabled = false;
    Cube.animation.Play();
   
   
   
      }
   
        }
        
        
       
    }

}



function OnTriggerExit () {
 if(Presses < 30){
 Presses = 0;
 Ekey.enabled = false;
 }
 else
 
 
 if(Presses == 30){

   Presses = 30;
   Ekey.enabled = false;

   }
}

OnTriggerEnter only gets called once, if you want the function to be called every frame that the collider is within the trigger then you can use OnTriggerStay() instead.