No movement to negative z-axis.

Hi,

I'm working with this 3D top down shooter game and try to get my character to look to the direction it's moving. I'm using joystick as a controller. Now it's looking where it should be going but not going there, not at least if the direction is negative z-axis. Any ideas?

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent (typeof (CharacterController))]
 public class JoystickLook : MonoBehaviour {
 
     public float speed = 10f;
 
     private CharacterController controller;
 
     private Vector3 input = Vector3.zero;
     private Vector3 motion = Vector3.zero;
         
 
     // Use this for initialization
     void Start () {
         controller = GetComponent<CharacterController> ();
     }
     
     // Update is called once per frame
     void Update () {
 
         input = new Vector3 (Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));
         input = input.normalized;
         
         if (input != Vector3.zero) {
             transform.rotation = Quaternion.LookRotation(input);
         }
         
         motion = input;
         motion *= speed;
 
         Debug.Log (motion);                
 
         controller.Move (motion * Time.deltaTime);
 
     }
 }