Character cannot move Diagonally forwards

I have been building a custom character controller from this set of tutorials Set of Tutorials. I can move diagonally backwards pressing the S and D keys or S and A but not forwards pressing W and A. I'm sure I've done everything right as they have said and have no idea why it is not working.

My Code: TP_Controller

 using UnityEngine;
 using System.Collections;
 
 public class TP_Controller : MonoBehaviour {
     
     public static CharacterController CharacterController;
     public static TP_Controller Instance;
     
     void Awake () 
     {
         CharacterController = GetComponent("CharacterController") as CharacterController;
         Instance = this;
     }
     
     // Update is called once per frame
     void Update () 
     {
         if (Camera.main == null)
             return;
         
         GetLocomotionInput();
         
         TP_Motor.Instance.UpdateMotor();
     }
     
     void GetLocomotionInput()
     {
         var deadZone = 0.1f;
         
         TP_Motor.Instance.MoveVector = Vector3.zero;
         
         if (Input.GetAxis("Vertical") > deadZone || Input.GetAxis("Vertical") < -deadZone)
             TP_Motor.Instance.MoveVector += new Vector3(0, 0, Input.GetAxis("Vertical"));
         
         if (Input.GetAxis("Horizontal") > deadZone || Input.GetAxis("Horizontal") < -deadZone)
             TP_Motor.Instance.MoveVector += new Vector3(Input.GetAxis("Horizontal"), 0, 0);
     }
     
 }

TP_Motor

 using UnityEngine;
 using System.Collections;
 
 public class TP_Motor : MonoBehaviour {
     
     public static TP_Motor Instance;
     
     public float MoveSpeed = 10f;
     
     public Vector3 MoveVector { get; set; }
     
     // Use this for initialization
     void Awake () 
     {
         Instance = this;
     }
     
     // Update is called once per frame
     public void UpdateMotor () 
     {
         SnapeAlignCharacterWithCamera();
         ProcessMotion();
     }
     
     void ProcessMotion()
     {
         // Transform MoveVector to World Space
         MoveVector  = transform.TransformDirection(MoveVector);
         
         // Normalize MoveVector if Magnitude > 1
         if (MoveVector.magnitude > 1)
             MoveVector = Vector3.Normalize(MoveVector);
         
         // Multiply MoveVector by MoveSpeed
         MoveVector *= MoveSpeed;
         
         // Multiply MoveVector by DeltaTime
         MoveVector *= Time.deltaTime;
         
         // Move the Character in World Space
         TP_Controller.CharacterController.Move(MoveVector);
     }
     
     void SnapeAlignCharacterWithCamera()
     {
         if (MoveVector.x != 0 || MoveVector.z != 0)
         {
         transform.rotation = Quaternion.Euler(transform.eulerAngles.x,Camera.main.transform.eulerAngles.y,transform.eulerAngles.z);
         }
     }
 }