Consuming Web Service in Xamarin

Hi Guys,
Trying to build my first Xamarin app. Got stuck on web services.
I am trying to replicate one of my app build in Android Native.
Getting stuck at authentication via web service. Using the same link which I have used in my native app.

While calling the web service there is no error (syntax) but there is no response back from web service.

Below are the link and credentials :

Link is http://service1.apwiz.com/service1.asmx
Function :- AuthenticateLoginWithBlankPassword
ID:- Admin
Pass:- admin@1