这个post方法哪里出了问题

[qq_25210351]

public static string HttpPost(string url, string param)
{
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.Accept = "*/*";
request.Timeout = 15000;
request.AllowAutoRedirect = false;
StreamWriter requestStream = null;
WebResponse response = null;
string responseStr = null;

try
{
requestStream = new StreamWriter(request.GetRequestStream());
requestStream.Write(param);
requestStream.Close();

response = request.GetResponse();
if (response != null)
{
StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
responseStr = reader.ReadToEnd();
reader.Close();
}
}
catch (Exception)
{
throw;
}
finally
{
request = null;
requestStream = null;
response = null;
}

return responseStr;
}

[qq_25210351]

这个方法 会报错 ，但是日志文件没记录我不知道错哪里了 ？因为我这边做个新浪授权的功能，这段代码调试不了，