I cant make my Character jump.

I already tried a lot of different ways to do this, and my character never jumps... Im using a character controller.

Heres my script: #pragma strict

 //Vars
 var WalkSpeed : int = 7;
 var Gravity : int = 20;
 var RotationSpeed : int = 5;
 var JumpHeight : int = 8;
 private var yRot : float;
 private var moveDirection : Vector3 = Vector3.zero;
 

 function Update () {
     var Controller : CharacterController = GetComponent(CharacterController);
     var vertical : Vector3 = transform.TransformDirection(Vector3.forward);
     var horizontal : Vector3 = transform.TransformDirection(Vector3.right);
     var height : Vector3 = transform.TransformDirection(Vector3.up);
     
     
     if(Input.GetAxis("Vertical")){
         Controller.Move((vertical * (WalkSpeed * Input.GetAxis("Vertical")))* Time.deltaTime);
         Controller.Move((horizontal * (WalkSpeed * Input.GetAxis("Horizontal")))* Time.deltaTime);
     
     }
     if(Input.GetAxis("Horizontal")){
         yRot += RotationSpeed * Input.GetAxis("Horizontal");
         transform.rotation = Quaternion.Euler(0, yRot,0);
         Controller.Move((horizontal * (WalkSpeed * Input.GetAxis("Horizontal")))* Time.deltaTime);
     }
     
       if (Input.GetButton ("Jump")) {
         if(Controller.isGrounded){ 
         moveDirection.y= JumpHeight;
      
     }
     }
     
   
     Controller.Move(height * - Gravity * 10 *Time.deltaTime);
 }
 
 well guys, i've made a new script and it works, thanks for the help anyway:

 var jumpSpeed : float = 8;
 var    gravity : float = 20;
 var turnSpeed : float = 90.0; 
 
 private var moveDirection : Vector3 = Vector3.zero;
 
 function Start () {
 
 }
 
 function Update () {
 
 var controller : CharacterController = GetComponent(CharacterController);
 
     if(controller.isGrounded)
     {
         moveDirection = Vector3(0, 0, Input.GetAxis("Vertical"));
         moveDirection = transform.TransformDirection(moveDirection);
         moveDirection *= speed;
         var turnAngle : float = turnSpeed * Input.GetAxis("Horizontal") * Time.deltaTime;
         transform.Rotate (0, turnAngle, 0);
         
         if(Input.GetButton("Jump")){
         
         moveDirection.y = jumpSpeed;
         
         }
     }
     
     moveDirection.y -= gravity * Time.deltaTime;
     
     controller.Move(moveDirection * Time.deltaTime); 
 
 }