Character Rotation - Script not functioning correctly

The problem with the script is that all but one of the diagonal movements are not functioning. I have a feeling that this is because the script is detecting that a key was pressed and not checking if the other key was pressed and going to the diagonal rotation.

JS

 public var time: Time;
 public var characterModel : GameObject;
 
 
 function Start () {
     time.fixedDeltaTime = 0.01f;
     
     characterModel = GameObject.Find("Gamemodel Combonation");
 }
 
 function FixedUpdate () {
 
 var yAngle = GameObject.Find("Main Camera").transform.eulerAngles.y;
 
  if (Input.GetKey(KeyCode.W))
      transform.eulerAngles = Vector3(0, yAngle, 0);
      
  if (Input.GetKey(KeyCode.W) && Input.GetKey(KeyCode.D))
      transform.eulerAngles = Vector3(0, yAngle + 45, 0);
     
  if (Input.GetKey(KeyCode.D))
      transform.eulerAngles = Vector3(0, yAngle + 90, 0);
  
  if (Input.GetKey(KeyCode.D) && Input.GetKey(KeyCode.S))
      transform.eulerAngles = Vector3(0, yAngle + 135, 0);
     
  if (Input.GetKey(KeyCode.S))
      transform.eulerAngles = Vector3(0, yAngle + 180, 0);
      
  if (Input.GetKey(KeyCode.S) && Input.GetKey(KeyCode.A))
      transform.eulerAngles + Vector3(0, yAngle + 225, 0);
     
  if (Input.GetKey(KeyCode.A))
      transform.eulerAngles = Vector3(0, yAngle + 270, 0);
      
  if (Input.GetKey(KeyCode.A) && Input.GetKey(KeyCode.W))
      transform.eulerAngles = Vector3(0, yAngle + 315, 0);
     
 }