Issues with connection to web service from xamarin

I Try to connect to web service from Xamarin of the following way:

public DataTable SeeArticles(string pStrCodeArticle) { DataTable x = new DataTable ();
WsLoc09.WSActividad ws = new CallRestService.WsLoc09.WSActividad ();// name web service WsLoc09 x=ws.SeeArticles (pStrCodeArticle);

        return x;
    }

I added the web reference to my app besides the web service that I'm using a local web service. The issue is when I try to access to web service or this is my idea...