unityscript - Unity Input.GetMouseButtonDown(0) is not working

My code to detect left mouse click is not working Input.GetMouseButtonDown(0) and Input.GetMouseButtonUp(0). But same code for Input.GetMouseButton(0) is working.

Code:

void FixedUpdate()
{
  #if UNITY_ANDROID
    mouseWorldPos = Camera.main.ScreenToWorldPoint(Input.mousePosition + new Vector3(0, 0, 4f));
    mouseCameraOffset = bowlingBall.position - mouseWorldPos;

    if (Input.GetMouseButtonDown(0))
    {
        Debug.Log("last");

        lastMousePos = Input.mousePosition;
    }