Cannot access a webservice via WP8 emulator

Question

I'm developing a windows phone 8 application which access another webservice. On the response code like:

private void OnGetResponse<TRequest, TResponse>(IAsyncResult result)
        {
            var state = (AsyncRequestState<TRequest, TResponse>)result.AsyncState;
            try
            {
                using (var webResponse = state.WebRequest.EndGetResponse(result))
                {
                  using (var responseStream = webResponse.GetResponseStream())
                  {
                    var response = formatter.Deserialize<TResponse>(responseStream);
                    state.TaskCompletionSource.SetResult(response);
                    state.Complete();
                  }
                }
            }
            catch (System.Exception ex)
            {

            }
           }
        }

when code executes this line

using (var webResponse = state.WebRequest.EndGetResponse(result))

error throws out saying: System.Net.WebException: The remote server returned an error: NotFound

But I can access the webservice via the built in IE. This means that the enumelator can access the internet. So what's the problem ? help please ~