为什么我对 Yobit.net 交换 API 的请求返回 404 错误？

我正在尝试完成信息请求。遵循了 api 的所有说明，但仍然得到 404。

我想执行来自 TradeApi getInfo 的请求。POST https://yobit.net/tapi/getInfo?nonce=1 标头：密钥：{api public key} 签名：{string "?nonce=1" 通过 HMAC-SHA512 用私钥编码}

响应总是 404。怎么了？

我附上代码。要求：

public APIResponse Request(string method, Dictionary<string, string> param = null, int ReRequestCount = 3)
{
    lock (locker)
        nonce = IncrementNonce();

    string urlParamStr = "?";
    using (HttpRequest request = new HttpRequest())
    {
        if (param != null)
            foreach (KeyValuePair<string, string> pair in param)
            {
                request.AddUrlParam(pair.Key, pair.Value);
                urlParamStr += pair.Key + "=" + pair.Value + "&";
            }
        request.AddUrlParam("nonce", nonce);
        urlParamStr += "nonce=" + nonce;
        string signedData = Get_HMAC_SHA512_Hash(Sign, urlParamStr);

        request.AddHeader("Key", Key);
        request.AddHeader("Sign", signedData);

        HttpResponse response = request.Post("https://yobit.net/tapi/" + method.ToString());
        if (response.StatusCode != HttpStatusCode.OK)
        {
            if (ReRequestCount > 0)
            {
                return Request(method, param, --ReRequestCount);
            }
            else
            {
                return null;
            }
        }
        else
        {
            return JsonConvert.DeserializeObject<APIResponse>(response.ToString());
        }
    }
}

HMAC 生成器：

public string Get_HMAC_SHA512_Hash(string key, string source)
{
    byte[] secretkeyBytes = Encoding.UTF8.GetBytes(key);
    byte[] inputBytes = Encoding.UTF8.GetBytes(source);
    using (var hmac = new HMACSHA512(secretkeyBytes))
    {
        byte[] hashValue = hmac.ComputeHash(inputBytes);

        string s = "";
        for (int i = 0; i < hashValue.Length; i++)
        {
            s += string.Format("{0:x2}", hashValue[i]);
        }
        return s;
        //return System.Convert.ToBase64String(hashValue);
    }
}