如何确定返回badrequest的请求的问题所在？

Question

我正在尝试在C＃中创建一个方法，该方法与https://app.profitshare.ro/files/pdf/api_affiliate.pdf中提供的最后一个示例代码等效。

var apiUser = "bogdan";
var apiKey = "111222333444555666777888999";
var phUrl = "http://api.profitshare.ro/affiliate-links/?";
var client = new HttpClient();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var now = DateTime.Now;
var time = now.ToString("r");
var queryString = "";
var signatureString = $"POSTaffiliate-links/?{queryString}/{apiUser}{time}";
        var request = new HttpRequestMessage(HttpMethod.Post, phUrl);
        request.Headers.Add("Date", time);
        request.Headers.Add("X-PS-Client", $"{apiUser}");
        request.Headers.Add("X-PS-Accept", "json");
        request.Headers.Add("X-PS-Auth", $"{HMAC_SHA1(signatureString, apiKey)}");
        request.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)");
        request.Content = new StringContent("{'name':'APIEmag','url':'www.emag.ro'}", Encoding.UTF8, "application/json");
        var response = client.SendAsync(request).Result;


//--------------------------------------------------------------------------
static string HMAC_SHA1(string signatureString, string secretKey)
    {
        var enc = Encoding.ASCII;
        HMACSHA1 hmac = new HMACSHA1(enc.GetBytes(secretKey));
        hmac.Initialize();

        byte[] buffer = enc.GetBytes(signatureString);
        return BitConverter.ToString(hmac.ComputeHash(buffer)).Replace("-", "").ToLower();
    }

我希望这段代码返回一个带有API返回的URL的JSON，但是每次都会收到BadRequest。我尝试了不同版本的useragent，但是结果是相同的。

最终使用RestClient（RestSharp）代替HttpClient，一切正常。