Chained payments with permissions 520003 Authentication failed - asp.net-mvc

Question

I have problem with executing chained payment after obtaining permission from user. I have no troubles to get Access Token and Access Token Secret.
The code should work this way: User (personal type sandbox account) authorizes primary receiver (business type sandbox account) to take money from his account.
Primary receiver sends a part of the sum to the second receiver.
The code is written in ASP.NET MVC but I suppose it has nothing to do with the framework, I'm using PayPalAdaptivePaymentsSDK and PayPalPermissionsSDK
I want to use it in sandbox environment for testing.
I assume it has something to do with application id, I would be very grateful for step-by-step explanation
Here's how I obtain all my credentials:
I login into my developer account.
account1.Username, account1.Password, account1.Signature
- sandbox -> accounts -> I select primary receiver of the payment (business type account) -> API Credentials
applicationId - "APP-80W284485P519543T"
In the config file I specified mode as "sandbox".
I use the same config for executing the payment.
Then I want to execute following code and in payResponse I get errorId 520003 "Authentication failed. API credentials are incorrect."
public class PermissionController : Controller
{
private AdaptivePaymentsService _adaptivePaymentService;
public ActionResult Index()
{
ViewBag.AccessToken = PayPalConfig.AccessToken;
ViewBag.AccessTokenSecret = PayPalConfig.AccessTokenSecret;
return View();
}
public PermissionController()
{
_adaptivePaymentService = new AdaptivePaymentsService(PayPalConfig.GetConfig());
}
public ActionResult GetPermission()
{
RequestPermissionsRequest rp = new RequestPermissionsRequest();
rp.scope = new List<string>();
rp.scope.Add("EXPRESS_CHECKOUT");
Dictionary<string, string> config = PayPalConfig.GetConfig();
rp.callback = "http://localhost:42072/Permission/GetAccessToken";
rp.requestEnvelope = new PayPal.Permissions.Model.RequestEnvelope("en_US");
RequestPermissionsResponse rpr = null;
PermissionsService service = new PermissionsService(config);
rpr = service.RequestPermissions(rp);
string confirmPermissions = "https://www.sandbox.paypal.com/webscr&cmd=_grant-permission&request_token=" + rpr.token;
return Redirect(confirmPermissions);
}
public ActionResult GetAccessToken()
{
Uri uri = Request.Url;
Dictionary<string, string> config = PayPalConfig.GetConfig();
var gat = new GetAccessTokenRequest();
gat.token = HttpUtility.ParseQueryString(uri.Query).Get("request_token");
gat.verifier = HttpUtility.ParseQueryString(uri.Query).Get("verification_code");
gat.requestEnvelope = new PayPal.Permissions.Model.RequestEnvelope("en_US");
GetAccessTokenResponse gats = null;
var service = new PermissionsService(config);
gats = service.GetAccessToken(gat);
_adaptivePaymentService.SetAccessToken(gats.token);
_adaptivePaymentService.SetAccessTokenSecret(gats.tokenSecret);
PayPalConfig.AccessToken = _adaptivePaymentService.getAccessToken();
PayPalConfig.AccessTokenSecret = _adaptivePaymentService.getAccessTokenSecret();
return RedirectToAction("Index");
}
public ActionResult ChainedPayment()
{
ReceiverList receiverList = new ReceiverList();
receiverList.receiver = new List<Receiver>();
Receiver secondaryReceiver = new Receiver(1.00M);
secondaryReceiver.email = "mizerykordia6662-facilitator#gmail.com";
receiverList.receiver.Add(secondaryReceiver);
Receiver primaryReceiver = new Receiver(5.00M);
primaryReceiver.email = "mizTestMerchant#test.com";
primaryReceiver.primary = true;
receiverList.receiver.Add(primaryReceiver);
PayPal.AdaptivePayments.Model.RequestEnvelope requestEnvelope = new PayPal.AdaptivePayments.Model.RequestEnvelope("en_US");
string actionType = "PAY";
string returnUrl = "http://localhost:42072/Home/Index";
string cancelUrl = "https://devtools-paypal.com/guide/ap_chained_payment/dotnet?cancel=true";
string currencyCode = "USD";
_adaptivePaymentService.SetAccessToken(PayPalConfig.AccessToken);
_adaptivePaymentService.SetAccessTokenSecret(PayPalConfig.AccessTokenSecret);
PayRequest payRequest = new PayRequest(requestEnvelope, actionType,
cancelUrl, currencyCode, receiverList, returnUrl);
// it breaks here
PayResponse payResponse = _adaptivePaymentService.Pay(payRequest);
PaymentDetailsRequest paymentDetailsRequest = new PaymentDetailsRequest(new PayPal.AdaptivePayments.Model.RequestEnvelope("en-US"));
paymentDetailsRequest.payKey = payResponse.payKey;
SetPaymentOptionsRequest paymentOptions = new SetPaymentOptionsRequest()
{ payKey = payResponse.payKey };
_adaptivePaymentService.SetPaymentOptions(paymentOptions);
PaymentDetailsResponse paymentDetailsRespons = _adaptivePaymentService.PaymentDetails(paymentDetailsRequest);
ExecutePaymentRequest exec = new ExecutePaymentRequest(new PayPal.AdaptivePayments.Model.RequestEnvelope("en-US"), paymentDetailsRequest.payKey);
ExecutePaymentResponse response = _adaptivePaymentService.ExecutePayment(exec);
return RedirectToAction("Index");
}
}