Payment API Returns AuthenticationFailed Error - php

Question

I am integrating payments to my app and using PHP-Payments-SDK from Intuit
When creating echeck debit by the following code.
public function echeck(Request $request){
$this->refreshToken();
$record = QuickbookModel::first();
$client = new PaymentClient([
'access_token' => $record->accessToken,
'environment' => "sandbox" // or 'environment' => "production"
]);
$array = [
"bankAccount" => [
"phone" => $request->phone,
"routingNumber" => $request->routingNumber,
"name" => $request->name,
"accountType" => $request->accountType,
"accountNumber" => $request->accountNumber
],
"description" => "Easyfi Testing",
"paymentMode" => "WEB",
"amount" => "5.55",
];
$bank = ECheckOperations::buildFrom($array);
$response = $client->debit($bank);
if($response->failed()){
$code = $response->getStatusCode();
$errorMessage = $response->getBody();
return json_encode(["status" => $code, "message" => $errorMessage]);
}else{
$responseCharge = $response->getBody();
//Get the Id of the charge request
$id = $responseCharge->id;
//Get the Status of the charge request
$status = $responseCharge->status;
return json_encode(["status" => $status, "message" => $responseCharge, "data" => $id]);
}
}
I always getting following error even everything is up to mark including Access Token
{status: 401, message: "{"code":"AuthenticationFailed","type":"INPUT","message":null,"detail":null,"moreInfo":null}"}