how to avoid e = {"Value does not fall within the expected range."} type error while sending json input to an webservice in windows phone 7 application

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WinMobile

Hi ,

I have created a one sample wp7 application in that in a login button click event , i am sending input in JSon type format to an webservice as shown below:

Here json is input data for authentication in JSon format.

private void ResponseCallBack(IAsyncResult result)
{
    try
    {
         string ret = string.Empty;
         StreamWriter requestWriter;
         if (request != null)
         {
            request.ContentType = "application/json; charset=utf-8";
            request = (HttpWebRequest)result.AsyncState;
            using (requestWriter = new StreamWriter(request.EndGetRequestStream(result)))
            {
                requestWriter.Write(json);
            }
         }
        response = (HttpWebResponse)request.EndGetResponse(result);
        using (var stream = response.GetResponseStream())
        {
            using (var reader = new StreamReader(stream))
            {
                ret = reader.ReadToEnd();
            }
        }
    }
    catch (Exception e)
    {

    }
}

But while executing the below statement from above code

using (var stream = response.GetResponseStream())
                {
                    using (var reader = new StreamReader(stream))
                    {
                        ret = reader.ReadToEnd();
                    }
                }

It show below error:

e = {"Value does not fall within the expected range."}

Please let me know the solution