try 
    {
        Credentials c = new Credentials(
                appName: "yourAppName",
                user: "yourUser",
                password: "yourPassword",
                version: "1.11",
                uri: "http://demo.subsonic.org"
                );
        Ping p = new Ping()
        {
            Credentials = c
        };
        //Call Ping
        var response = await p.DoRequest<PingResponse>();
    }
    catch(SubsonicException se)
    {
        Console.WriteLine(se.Error.Details.message);
    }