نحوه استفاده از open street api

با سلام

من یه وب سرویس با WCF نوشتم که داخل اون از OpenStreet Api استفاده کردم ولی یه جا بهم خطای parameter is not valid میده.

ممنون

اینم کدمه:

        public byte[] GetPlacePhoto(double? lat, double? lng, int? zoomx, string scriptoriumId)

        {

            var watch = new Stopwatch();

            watch.Start();

            try

            {

                #region checkRangeInputs



                //if (sizeH == null)

                //    throw new ArgumentOutOfRangeException("sizeH is NULL!");

                //if (sizeW == null)

                //    throw new ArgumentOutOfRangeException("sizeH is NULL!");

                if (lat == null)

                    throw new ArgumentOutOfRangeException("lat is NULL!");

                if (lng == null)

                    throw new ArgumentOutOfRangeException("lng is NULL!");

                if (zoomx == null)

                    throw new ArgumentOutOfRangeException("zoomx is NULL!");

                if (string.IsNullOrEmpty(scriptoriumId))

                    throw new ArgumentOutOfRangeException("scriptoriumId is NULL!");



                //if (sizeH <= 0 || sizeH >= 1600)

                //    throw new ArgumentOutOfRangeException("sizeH out off range (range between 0,1600)");

                //if (sizeW <= 0 || sizeW >= 1600)

                //    throw new ArgumentOutOfRangeException("sizeW out off range (range between 0,1600)");



                #endregion



                //string size = sizeH + "x" + sizeW;

                string requeststring = "https://www.openstreetmap.org/#map=" + zoomx + "/" + lng + "/" + lat;

                WebRequest request = WebRequest.Create(requeststring);

                request.ContentType = "application/json; charset=utf-8";

                WebResponse response = request.GetResponse();



                if (response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))

                {

                    using (Stream inputStream = response.GetResponseStream())

                    {

                        Image imageIn = Image.FromStream(inputStream);

                        MemoryStream ms = new MemoryStream();

                        imageIn.Save(ms, ImageFormat.Png);

                        byte[] imagebyte = ms.ToArray();

                        string jsonResponse = JsonConvert.SerializeObject(response);



                        CreateScriptoriumImageLog(jsonResponse, requeststring, scriptoriumId, convert_milisecond_to_hms(watch.ElapsedMillisecond  s));

                        return imagebyte;

                    }

                }

                else

                {

                    CreateScriptoriumImageErrorLog("API Can Not Return Photo: ", response.ToString(), requeststring, scriptoriumId, convert_milisecond_to_hms(watch.ElapsedMillisecond  s));

                    throw new FaultException("API Can Not Return Photo: " + response);

                }

            }

            catch (Exception ex)

            {

                CreateImageExceptionErrorLog("Exception: " + ex, convert_milisecond_to_hms(watch.ElapsedMillisecond  s));

                throw new FaultException("Exception: " + ex);

                return null;



            }

            finally

            {

                watch.Stop();

            }

        }

توی این خطی که نوشتم خطا میده:

Image imageIn = Image.FromStream(inputStream);

ممنون میشم از دوستان کمکم کنند و بگن چکار کنم؟