Unity 3d GUI text problem PLEASE HELP :|

Hello guys its again me, so i am new to unity3d but i know a bit of javaScript i’ve again one more question about GUI textSo there is my script i want make shooting counter so yeah,
there is script:
#pragma strict

var targetGuiText : GUIText;
var Ammo = 30;

function Update()
if (Input.GetMouseButtonDown(0))
Ammo -=1;
targetGuiText.text = Ammo;

targetGuiText.text = Ammo.ToString();

Probably this is the problem.

By the way, we are not mind readers, you must write/mention all possible information related to your problem.
By this i mean:

*Say on what line the error is.

*Error itself

*How you have tried solving your own problem.