помогите пожалуйста error CS0103: The name 'Advertisement' does not exist in the current context

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Advertisements;

public class player : MonoBehaviour
{
    public Text textxt;

    public decimal money = 0m;



    void Start()
    {
        if (Advertisement.isSupported)
        {
            Advertisement.Initialize("4733355",false);
        }
    }
    void Update()
    {
        textxt.text = money + "";
    }

    public void KrClick()
    {
        if (true)
        {
            money += 0.00000002m;
        }
    }

    public void KrClick2()
    {
        if (true)
        {
            money += 0.20m;
            if (Advertisement.IsReady())
            {
                Advertisement.Show("video");
            }
            
        }
    }
}

Ошибка:

error CS0103: The name 'Advertisement' does not exist in the current context