Touch Hd screen drag problems

Hi!

I have a problem. When I use a typical dragging script (drag and rotates a gameobject) it works fine with my pc and in Android too, but when I use the exe in a touch hd screen the dragging doesn't work. Why it happens?

check by yourself, why it works only in andrid touches and with windows mouse?:

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using UnityEngine; using System.Collections;

public class drager : MonoBehaviour {

 private bool dragging = false;    
 private float distance;


 void OnMouseDown()    
 {
     distance = Vector3.Distance(transform.position , Camera.main.transform.position);    
     dragging = true;    
 }
 
 void OnMouseUp()
 {
     dragging = false;    


 }
 
 void Update()
 {    
     if (dragging)    
     {
         float distance_to_screen = Camera.main.WorldToScreenPoint(gameObject.transform.position).z;
         Vector3 pos_move = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, distance_to_screen ));
         transform.position = new Vector3( pos_move.x, pos_move.y, pos_move.z );

     }

 }

}