ARKit: Object not appear when i touch the screen

Hi, i do follow ARKit tutorial from youtube. then i want one object only that appear when i touch the screen so i read the comment said that i can make it by adding some script in it. But when i add the new script it appear nothing when i touched the screen. There is no error when i run this code but it just not working.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.XR.ARFoundation;
using UnityEngine.Experimental.XR;
using System;

public class ARTapToPlaceObject : MonoBehaviour
{
public GameObject objectToPlace;
public GameObject placementIndicator;

private ARSessionOrigin arOrigin;
private Pose placementPose;
private bool placementPoseIsValid = false;
private bool placementIsComplete = false;

void Start()
{
arOrigin = FindObjectOfType<ARSessionOrigin>();
}

void Update()
{
UpdatePlacementPose();
UpdatePlacementIndicator();


//if (placementPoseIsValid && Input.touchCount < 0 || (Input.GetTouch(0)).phase != TouchPhase.Began)

if (placementPoseIsValid && Input.touchCount < 0 && Input.GetTouch(0).phase == TouchPhase.Began)
{
PlaceObject();
}
}

private void PlaceObject()
{
placementIsComplete = true;
Instantiate(objectToPlace, placementPose.position, placementPose.rotation);
}


private void UpdatePlacementIndicator()
{
if (!placementIsComplete && placementPoseIsValid)
{
placementIndicator.SetActive(true);
placementIndicator.transform.SetPositionAndRotation(placementPose.position, placementPose.rotation);
}

else
{
placementIndicator.SetActive(false);
}
}

private void UpdatePlacementPose()
{

var screenCenter = Camera.current.ViewportToScreenPoint(new Vector3(0.5F, 0.5F));
var hits = new List<ARRaycastHit>();
arOrigin.Raycast(screenCenter, hits, TrackableType.Planes);

placementPoseIsValid = hits.Count > 0;

if (placementPoseIsValid)
{


placementPose = hits[0].pose;


var cameraForward = Camera.current.transform.forward;
var cameraBearing = new Vector3(cameraForward.x, 0, cameraForward.z).normalized;
placementPose.rotation = Quaternion.LookRotation(cameraBearing);
}

}

}



Someone please help me fix this