Wrong WorldToScreenPoint converting (not inverted y)

Hey. I have GameObject under character head and want to see character's nickname in this position. Here my code

 using System;
 using SCdll.NSServer;
 using SCdll.NSServer.ServerInterface;
 using UnityEngine;
 using System.Collections;
 
 public class ClientControl : MonoBehaviour
 {
 
     public CharInfo newData, lastData, info;
     private Animator animator;
     public float speed = 1;
     private Transform myTransform;
     private CharacterController controller;
     private Vector3 velocity, pointPos;
     public float time;
     public ushort messageID = 0;
     public int UserID;
     private GUIStyle style;
     private Transform nickPoint;
     private Vector3 screen;
     private Vector2 nickSize;
     private float distance;
     private float multiplier;
     private float x;
     private float y;
     private Vector3 viewPortPos;
     private Transform mesh;
 
     // Use this for initialization
     private void Start()
     {
         mesh = transform.FindChild("mesh");
         animator = transform.FindChild("mesh").GetComponent<Animator>();
         myTransform = transform;
         velocity = Vector3.zero;
         controller = transform.GetComponent<CharacterController>();
 
         style = new GUIStyle();
         style.alignment = TextAnchor.LowerCenter;
         style.normal.textColor = Color.black;
         style.fontSize = 19;
         style.fontStyle = FontStyle.Bold;
         nickPoint = transform.FindChild("nick");
         screen = Camera.main.ViewportToScreenPoint(Camera.main.WorldToViewportPoint(nickPoint.transform.position));
         nickSize = style.CalcSize(new GUIContent(TempStorage.nickname));
         x = -11/90f;
         y = 182/9f;
     }
 
     // Update is called once per frame
     void Update()
     {
         distance = Vector3.Distance(myTransform.position, Camera.main.transform.position);
         if (distance <= 10)
         {
             style.fontSize = 19;
         }
         else if (distance >= 100)
         {
             style.fontSize = 8;
         }
         else
         {
             style.fontSize = (int) Math.Floor(distance*x + y);
         }
        // Debug.Log("Font size is: " + style.fontSize + " Distance is: " + distance);
     }
 
     void OnGUI()
     {
         if (info != null)
         {
             viewPortPos = Camera.main.WorldToViewportPoint(nickPoint.transform.position);
            // Debug.Log("viewPortPos: " + viewPortPos);
             if (viewPortPos.x >= 0 && viewPortPos.x <= 1 && viewPortPos.y >= 0 && viewPortPos.y <= 1 && viewPortPos.z>0
                 && !Physics.Linecast(nickPoint.transform.position,Camera.main.transform.position) && distance<=100)
             {
                 screen = Camera.main.WorldToScreenPoint(nickPoint.transform.position);
                 GUI.Label(new Rect(screen.x - 25, Screen.height-screen.y, 50, 25), info.NickName,style);
             }
         }
 
     }
 }

What is my problem? When the character goes far away then nickname goes down. I don't know why, really, no idea... Maybe someone knows why it happens? p.s. here is my video proof, pink sphere - point where nickname must be VIDEO