help with script

hi im having a probelm im trying to make a ammo box and make it so that when i pick it up the box gets destroyed and im trying to us a vtc course but it seems not to work for me i even tryed to use raycasting but nothing im trying to make this happen upon collision here is my scrip

but nothing happens when i run into the box
and the box is taged

static var GRENADE_AMMO = 1;

function OnControllerColliderHit(hit : ControllerColliderHit)

{

  if(hit.gameObject.tag == "crateGrenades")
 {
	 //destroy the ammo box
	 Destroy(hit.gameObject);
	 
	 //add ammo to invetory
	 GRENADE_AMMO += 10;

     
 }	 

}

Since grenade Ammo is static, you need to reference the name of the script that GRENADE_AMMO is stored. For example, if GRENADE_AMMO was in a script called “WeaponManager”, you would need to have WeaponManager.GRENADE_AMMO += 1 not GRENADE_AMMO += 1.

ok so i have found the awnser it is because the script was attached to the main camrea not the first person controler