Unknown identifier "other"

I tried to use other.CompareTag but just received an error saying that other is an unknown identifier? can anyone help me?

#pragma strict
var Slow = 0.5;
function Start () {

}

function Update () {
}

function OnTriggerStay(Bullet : Collider) 
{	//the "other" below this text is the one cauisng trouble it seems
if (other.CompareTag ("Bullet")) 
	{
	Time.timeScale = Slow;
	
	Time.fixedDeltaTime = 0.02 * Time.timeScale;
	}
}

function OnTriggerExit(Bullet : Collider)
{	//the "other" below this text is the one cauisng trouble it seems
if(other.CompareTag ("Bullet"))
	{
	Time.timeScale = 1;
	
	Time.fixedDeltaTime = 0.02 * Time.timeScale;
	}
}

[32218-inspector+1.png|32218]

Replace

if(other.CompareTag ("Bullet"))

with

if(Bullet.CompareTag ("Bullet"))