I'm trying to do a health system via GUItext heres the code I have for the GUIText its in java script but here

var score = 0;
function Update () {
var text = "Health: ";
guiText.text = text + score.ToString();
}

and heres the code I have for when the zombie collides with the player

var score = 1; 
var GUIhealth : GUIText;

function OnTriggerEnter( other : Collider ) 
{ 
if (other.tag == "zom") 
{
score++; 
GUIhealth.text = score.ToString();
} 
}

but the text isnt updateing when the zombie hits the player the gui text is named GUIhealth but it isnt working:/ what am I doing wrong?