simple touch input test isn't working

Hi I am a new to unity3d and I am trying to detect the number of touch input in an android game but it doesn't working. I checked the code many time but nothing seems wrong. Am I missing something? It's a simple code.

 void Update ()     
     {
         bool supportsMultiTouch = Input.multiTouchEnabled;
         print("MultiTouchSupport : " + supportsMultiTouch);
 
         int nbTouches = Input.touchCount;
         if(nbTouches >= 0){
             print(nbTouches + " touch(es) detected");
             for (int i = 0; i < nbTouches; i++)
             {
                 touch = Input.GetTouch(i);
                 print("Touch index " + touch.fingerId + " detected at position " + touch.position);
             }
         }
     }