使用Post方法将XML数据发送到服务器

Question

我正在尝试将xml数据发送到Web服务器，但是当我发送数据时出现错误，System.Net.WebException：'远程服务器返回错误：（500）内部服务器错误。“，

这是我的代码：

 public string postXMLData(string soap_action, string requestXml)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(@"https://secure.yieldplanet.com/XmlServices/ChannelManager.asmx");
        request.Headers.Add(@"SOAPAction:XmlServices/" + soap_action);
        request.ContentType = "text/xml; encoding='utf-8'";
        request.Accept = "text/xml";
        request.Method = "POST";
        byte[] bytes;
        bytes = System.Text.Encoding.ASCII.GetBytes(requestXml);
        request.ContentLength = bytes.Length;
        Stream requestStream = request.GetRequestStream();
        requestStream.Write(bytes, 0, bytes.Length);
        requestStream.Close();
        HttpWebResponse response;
        response = (HttpWebResponse)request.GetResponse();
        if (response.StatusCode == HttpStatusCode.OK)
        {
            Stream responseStream = response.GetResponseStream();
            string responseStr = new StreamReader(responseStream).ReadToEnd();
            return responseStr;
        }
        return null;
    }

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