Health will not minus correctly

I have a health script that is on my player:

var maxHealth : int = 100;
public static var currentHealth : int = 100;
var PlayerHealthDisplay : GUIText;

function Start() {
    DisplayAmount();
}

function DisplayAmount () {
    PlayerHealthDisplay.text = ""+ currentHealth;
}

function Update () {
	
	if(currentHealth < 0) {
		currentHealth = 0;
	}
	
	if(currentHealth > maxHealth) {
		currentHealth = maxHealth;
	}
	
	if(maxHealth < 1) {
		maxHealth = 1;
	}
	
	if(currentHealth < 0) {
		//Application.LoadLevel ("Gameover");
	}	
}

And this on an empty collider that has is trigger check:

function OnTriggerEnter(other : Collider){
    if (other.CompareTag("Player")){
        PlayerHealth.currentHealth -= 10;
        
         }
       }

but it never minus the health from the charactor and I cant figure out why

I believe you have the DisplayHealth missing in the Update statement. You are initializing the health text to the current value, but never updating after it changes. And to help, in my opinion, I think you should change the code to do something as such (to avoid unnecessary processing during the update):

var maxHealth : int = 100;
public static var currentHealth : int = 100;
var PlayerHealthDisplay : GUIText;

function Start() {
    DisplayAmount();
}

function DisplayAmount () {
    PlayerHealthDisplay.text = ""+ currentHealth;
}

function ApplyHealth(value : int) {
    currentHealth += value;

    if(currentHealth < 0) {
       currentHealth = 0;
       //Application.LoadLevel ("Gameover");
    }
    else if(currentHealth > maxHealth) {
       currentHealth = maxHealth;
    }

    DisplayAmount();
}

function SetMaxHealth(value : int) {
    if(value < 1) {
       maxHealth = value;
    }
}

And use the following for the trigger:

function OnTriggerEnter(other : Collider) {
    if (other.CompareTag("Player")) {
        PlayerHealth ph = other.GetComponent(PlayerHealth)
        ph.ApplyHealth(-10);
     }
}

125**Replace your first script with this one:**125

var maxHealth : int = 100;

public static var currentHealth : int = 100;

var PlayerHealthDisplay : GUIText;

function Start() {
DisplayAmount();
}

function DisplayAmount () {
PlayerHealthDisplay.text = “”+ currentHealth;
}

function Update () {

if(currentHealth <= 0) {
   currentHealth = 0;
}

if(currentHealth >= maxHealth) {
   currentHealth = maxHealth;
}

if(maxHealth <= 1) {
   maxHealth = 1;
}

if(currentHealth <= 0) {
   //Application.LoadLevel ("Gameover");
}  

}

instead of the CompareTag, use other.gameObject.tag
and your current health should not be a static var.

var maxHealth : int = 100;
var currentHealth : int = 100;
var PlayerHealthDisplay : GUIText;

function Start() {
DisplayAmount();
}

function DisplayAmount () {
PlayerHealthDisplay.text = “”+ currentHealth;
}

function Update () {

if(currentHealth < 0) {
   currentHealth = 0;
}

if(currentHealth > maxHealth) {
   currentHealth = maxHealth;
}

if(maxHealth > 1) {
   maxHealth = 1;
}

if(currentHealth < 0) {
   //Application.LoadLevel ("Gameover");
}  

}

//And this on an empty collider that has is trigger check:

function OnTriggerEnter(other : Collider){
if (other.gameObject.tag == “Player”){
PlayerHealth.currentHealth -= 10;

     }
   }