MWS Financial Services client library returning a null exception

Question

I made a very simple console application which will hit MWS service and return XML document containing list of financial events. As it starts, an exception hits at line 14 'client.ListFinancialEvents(request)' and it just show null and no other information as to why its not working.

string accessKey = "AccessKey";
string secretKey = "SecretKey";
string appName = "AppName";
string appVersion = "1.0";
string serviceURL = "http://mws.amazonservices.com/Finances/2015-05-01/";
try
{
    MWSFinancesServiceConfig config = new MWSFinancesServiceConfig();
    config.ServiceURL = serviceURL;
    MWSFinancesServiceClient client = new MWSFinancesServiceClient(accessKey, secretKey, appName, appVersion, config);
    ListFinancialEventsRequest request = new ListFinancialEventsRequest();
    request.SellerId = "SellerID";
    request.AmazonOrderId = "111-111111111-111111111";
    ListFinancialEventsResponse response = client.ListFinancialEvents(request);
    Console.WriteLine("Response:");
    ResponseHeaderMetadata rhmd = response.ResponseHeaderMetadata;
    Console.WriteLine("RequestId: " + rhmd.RequestId);
    Console.WriteLine("Timestamp: " + rhmd.Timestamp);
    string responseXml = response.ToXML();
    Console.WriteLine(response.ResponseHeaderMetadata);
}
catch (Exception e)
{
    Console.WriteLine("Error: " + e.Message);
}
Console.ReadLine();

The DLLs used as reference were downloaded from here. I have already tried MWS Scratchpad and values are working fine. What could be the possible issues due to which this exception occurred and how to solve this issue?

Answer 1

I am posting an answer to my own question in case someone faces similar issue in the future.

I was making a very stupid mistake and it took me a week to figure it out. In service URL, instead of "http://..." it should be "https://..." and it starts working perfectly. It return complete XML as response in 'responseXml' variable.