BigCommerce OAuth“无效范围”;错误

我试图从BigCommerce检索访问令牌。我按照这个页面上的说明:https://developer.bigcommerce.com/apps/callback

当我尝试检索访问令牌时，我得到一个无效的作用域错误。下面是代码:

    public function access_token_get(){
            print_r($_GET);
            $tokenUrl = "https://login.bigcommerce.com/oauth2/token";
            $connection = new Connection();
            $connection->setCipher('RC4-SHA');
            $connection->verifyPeer(false);
            $response = $connection->post($tokenUrl, array(
                "client_id" => "123456",
                "client_secret" => "123456",
                "redirect_uri" => "https://my-registered-auth-callback.com/",
                "grant_type" => "authorization_code",
                "code" => urlencode($_GET['code']),
                "scope" => urlencode($_GET['scope']),
                "context" => urlencode($_GET['context'])
            ));
            print_r($response);
            print_r($connection->getLastError());
            $token = $response->access_token;
            print_r($token);
    }

当这段代码运行时，我得到一个空的$response。我添加了getLastError()行来看看发生了什么，它输出了:

stdClass Object ( [error] => Invalid scope(s). )

这些是GET请求输出的参数:

Array ( [code] => 2idy1ozvee8s0ddlbg3jgquzgtr55gd [context] => stores/xxxxxx [scope] => store_v2_orders store_v2_products store_v2_customers store_v2_content store_v2_marketing store_v2_information_read_only users_basic_information )

为什么我会收到这个"无效作用域"错误?我还尝试硬编码单个作用域，看看是否有效，例如，只是做"scope"=>"store_v2_orders"，但是当我这样做时，我得到一个错误，说该作用域尚未被用户授予。