problem with touch android

hello I have a problem (perhaps trivial) with the touch. The objective of the game is to click on the blue balls for points. These balls are constantly changing color so if I click that are colored red, yellow, green should take points. I tested the project is for PC for Android. For PC works great for Android, not much. Sometimes when I click on the blue balls it takes away points instead of accumulate. Here's the script: Touch;

 function Update () 
 
 {
 
    //loop through all registered touches
 
    for (var i = 0; i < Input.touchCount; ++i) 
 
    {
 
      if (Input.GetTouch(i).phase == TouchPhase.Began) 
 
      { 
 
        var hit : RaycastHit;
 
        var ray = Camera.main.ScreenPointToRay (
 
 Input.GetTouch(i).position
 
 );
 
        if (Physics.Raycast (ray, hit, 10000))
 
        {
 
           Destroy(hit.transform.gameObject);
 
           gameObject.Find("Sphere(Clone)").SendMessage("Tablet");
 
           
 
        }
 
        
 
      }
 
    }
 
 }

Color random:

 #pragma strict
 
  
 
 var texBall : Texture[] = new Texture [5];
 
  
 
 var randomtex : int;
 
  
 
 function Start(){
 
  
 
  
 
  
 
  
 
 textureRandom(); //esegui la funzione textureRandom
 
  
 
  collider.enabled = true;
 
 }
 
  
 
 function update(){
 
  
 
  
 
  
 
 }
 
  
 
  
 
  
 
 function textureRandom(){
 
  
 
  
 
  
 
 while(true){ //finchè è vero esegui il ciclo
 
     
 
     yield WaitForSeconds(1); //aspetto 1 secondo e cambio colore alla mesh
 
     
 
      // variabile randomColor
 
     
 
      randomtex = Random.Range(0, texBall.length); //random della variabile cambiaColore
 
     
 
       
 
    renderer.material.mainTexture= texBall[randomtex]; // lo assegno alla variabile randomColor
 
     
 
     
 
  if( randomtex == 0) { //Se rossa
 
  collider.enabled = true; //attivo collider
 
  
 
  
 
  
 
  //print("collider attivo");
 
  
 
  }
 
  
 
  else{
 
  
 
  collider.enabled = true; //altrimenti disattivo
 
  
 
  
 
  }
 
  
 
 }
 
 }
 
  
 
 function Tablet(){ //se collider attivo 
 if(randomtex == 3){ //rosso
 
 Destroy(gameObject);
 
 gameObject.Find("Main Camera").SendMessage("aggiorna");
 gameObject.Find("Main Camera").SendMessage("sound");
 }
 
 
 else{
 
 gameObject.Find("Main Camera").SendMessage("decrementa");
 
 
 }
 
 
 }