RevenueCat Unity, error: EntryPointNotFoundException: _RCSetupPurchases

Question

I implement in my project RevenueCat and it doesn't see my purchases only installs. I make all like in guide

https://docs.revenuecat.com/v1.0/docs/setting-up-unity-sdk

This is my code:

using UnityEngine;
using System.Collections;
using System;
using System.Globalization;
using System.Collections.Generic;
using System.Runtime.InteropServices;

#pragma warning disable CS0649

public class Purchases : MonoBehaviour
{
public abstract class Listener : MonoBehaviour
{
    public abstract void ProductsReceived(List<Product> products);
    public abstract void PurchaseCompleted(string productIdentifier,       Error error, PurchaserInfo purchaserInfo, bool userCanceled);
    public abstract void PurchaserInfoReceived(PurchaserInfo purchaserInfo);
}

/*
 * PurchaserInfo encapsulate the current status of subscriber. 
 * Use it to determine which entitlements to unlock, typically by checking 
 * ActiveSubscriptions or via LatestExpirationDate. 
 * 
 * Note: All DateTimes are in UTC, be sure to compare them with 
 * DateTime.UtcNow
 */
public class PurchaserInfo
{
    private PurchaserInfoResponse response;
    public PurchaserInfo(PurchaserInfoResponse response)
    {
        this.response = response;
    }


    public List<string> ActiveSubscriptions
    {
        get
        {
            return response.activeSubscriptions;
        }
    }

    public List<string> AllPurchasedProductIdentifiers
    {
        get
        {
            return response.allPurchasedProductIdentifiers;
        }
    }

    public DateTime LatestExpirationDate 
    {
        get
        {
            return DateTime.Parse(response.latestExpirationDate, null, DateTimeStyles.RoundtripKind );
        }
    }

    public Dictionary<string, DateTime> AllExpirationDates
    {
        get
        {
            Dictionary<string, DateTime> allExpirations = new Dictionary<string, DateTime>();
            for (int i = 0; i < response.allExpirationDateKeys.Count; i++)
            {
                var date = DateTime.Parse(response.allExpirationDateValues[i], null, DateTimeStyles.RoundtripKind | DateTimeStyles.AdjustToUniversal);
                if (date != null)
                {
                    allExpirations[response.allExpirationDateKeys[i]] = date;
                }
            }
            return allExpirations;
        }
    }

}

[Serializable]
public class Error
{
    public string message;
    public int code;
    public string domain;
}

[Serializable]
public class Product
{
    public string title;
    public string identifier;
    public string description;
    public float price;
    public string priceString;
}

[Tooltip("Your RevenueCat API Key. Get from   https://app.revenuecat.com/")]
public string revenueCatAPIKey;

[Tooltip("App user id. Pass in your own ID if your app has accounts.   If blank, RevenueCat will generate a user ID for you.")]
public string appUserID;

[Tooltip("List of product identifiers.")]
public string[] productIdentifiers;

[Tooltip("A subclass of Purchases.Listener component. Use your custom  subclass to define how to handle events.")]
public Listener listener;

void Start()
{
   // string appUserID = (this.appUserID.Length == 0) ? null : this.appUserID;
    PurchasesWrapper.Setup(revenueCatAPIKey);
    PurchasesWrapper.GetProducts(productIdentifiers);
}

// Call this to initialte a purchase
public void MakePurchase(string productIdentifier, string type = "subs")
{
    PurchasesWrapper.MakePurchase(productIdentifier, type);
}

[Serializable]
private class ProductResponse {
    public List<Product> products;
}

private void _receiveProducts(string productsJSON)
{
    ProductResponse response = JsonUtility.FromJson<ProductResponse>(productsJSON);
    listener.ProductsReceived(response.products);
}

[Serializable]
private class ReceivePurchaserInfoResponse 
{
    public string productIdentifier;
    public PurchaserInfoResponse purchaserInfo;
    public Error error;
}

[Serializable]
public class PurchaserInfoResponse
{
    public List<string> activeSubscriptions;
    public List<string> allPurchasedProductIdentifiers;
    public string latestExpirationDate;
    public List<string> allExpirationDateKeys;
    public List<string> allExpirationDateValues;
}

private void _receivePurchaserInfo(string arguments)
{
    var response = JsonUtility.FromJson<ReceivePurchaserInfoResponse>(arguments);

    var error = (response.error.message != null) ? response.error : null;
    var info = (response.purchaserInfo.activeSubscriptions != null) ? new PurchaserInfo(response.purchaserInfo) : null;


    if (response.productIdentifier != null) 
    {
        bool userCanceled = (error != null && error.domain ==  "SKErrorDomain" && error.code == 2);
        listener.PurchaseCompleted(response.productIdentifier, error, info, userCanceled);
    } else if (info != null) 
    {
        listener.PurchaserInfoReceived(info);
    }
}
}

And this is the second:

using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using UnityEngine;


public class PurchasesWrapper: Purchases
{
[DllImport("__Internal")]
private static extern void _RCSetupPurchases(string apiKey);
public static void Setup(string apiKey)
{
    _RCSetupPurchases(apiKey);
}

public class ProductsRequest
{
    public string[] productIdentifiers;
}

[DllImport("__Internal")]
private static extern void _RCGetProducts(string  productIdentifiersJSON, string type);
public static void GetProducts(string[] productIdentifiers, string type = "subs")
{
    ProductsRequest request = new ProductsRequest
    {
        productIdentifiers = productIdentifiers
    };

    _RCGetProducts(JsonUtility.ToJson(request), type);
}

[DllImport("__Internal")]
private static extern void _RCMakePurchase(string productIdentifier, string type);
public static void MakePurchase(string productIdentifier, string type = "subs")
{
    _RCMakePurchase(productIdentifier, type);
}
}

I get this error

EntryPointNotFoundException: _RCSetupPurchases PurchasesWrapper.Setup (System.String apiKey) (at Assets/Plugins/PurchasesWrapper.cs:14) Purchases.Start () (at Assets/Plugins/Purchases.cs:113)

What can it be? I set my key, and I tried to set it at start scene and at purchase scene, the same thing.What can it be?