USPS shippingapis returns "400 Bad Request"

Can anyone help me with this. var response = request.GetResponse(); returns "400 Bad Request" in proc

private string DoRequest(string url, string requestString)
        {
            byte[] bytes = new ASCIIEncoding().GetBytes(requestString);
            var request = (HttpWebRequest)WebRequest.Create(url); 
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            request.ContentLength = bytes.Length;
            var requestStream = request.GetRequestStream();
            requestStream.Write(bytes, 0, bytes.Length);
            requestStream.Close();
            var response = request.GetResponse();
            string responseXML = string.Empty;
            using (var reader = new StreamReader(response.GetResponseStream()))
                responseXML = reader.ReadToEnd();

            return responseXML;
        }

value of requestString is :

API=RateV3&XML=<RateV3Request USERID=\"MYUSR\" PASSWORD="MYPWD"><Package ID="0"><Service>ALL</Service><ZipOrigination>90503</ZipOrigination><ZipDestination>90210</ZipDestination><Pounds>2</Pounds><Ounces>0</Ounces><Size>Regular</Size><Machinable>FALSE</Machinable></Package></RateV3Request>

and value of url is:

http://production.shippingapis.com/ShippingAPI.dll

USPS approve me production request. I am trying to get this from VS in local environment.

nopCommerce version is 1.9.

Thanks!

Did they change your account to active? I had same issue and this cleared it up.

Mark