Amazon MWS c# Products GetCompetitivePricingForSKU抛出异常

当我试图请求产品的有竞争力的价格时，我总是得到一个

MarketplaceWebServiceProductsException

Message是空的，TargetSite给了我

T Call[T](MWSClientCsRuntime.IMwsRequestType1[T], MWSClientCsRuntime.IMwsObject)

这是我正在运行的代码

        MarketplaceWebServiceProducts.MarketplaceWebServiceProducts service = new MarketplaceWebServiceProductsClient (config.MWS_AccessKeyId, config.MWS_secretKey);
        SellerSKUListType list = new SellerSKUListType ();
        List<String> SKUList = new List<String> ();
        SKUList.Add (SKU);
        list.SellerSKU = SKUList;
        GetCompetitivePricingForSKURequest request = new GetCompetitivePricingForSKURequest ();
        request.MarketplaceId = config.MWS_MarketPlaceId;
        request.SellerId = config.MWS_SellerId;
        request.SellerSKUList = list;
        GetCompetitivePricingForSKUResponse response = service.GetCompetitivePricingForSKU (request);

var config = new MarketplaceWebServiceProductsConfig();
config.ServiceURL = "https://mws.amazonservices.com/Products/2011-10-01";
config.SetUserAgent(ApplicationName, ApplicationVersion);
var service = new MarketplaceWebServiceProductsClient(ApplicationName, ApplicationVersion, MWSaccessKey, MWSsecretKey, config);