XML Parser / Android / XmlTextReader

I'm new to Xamarin environnement and I get an error when my code reach " while reader.read I'v tried to do reader.read in a test application and the application crash and i get this error

"Could not find a part of the path "/ http:/www.ezzylearning.com/services/CountryInformationService.asmx/GetCountries**" ** http://hpics.li/49c2c94

Note: this is perfectly working in my other C# Applicaion / ASP Web Application Is this functionnality supported in Xamarin or not ? How can I parse XML from url easily with C# Xamarin ?

        // Get our button from the layout resource,
        // and attach an event to it
        Button button = FindViewById<Button> (Resource.Id.myButton);
        TextView Myview = FindViewById<TextView> (Resource.Id.textView1);

        String URLString = " http://www.ezzylearning.com/services/CountryInformationService.asmx/GetCountries";
        XmlTextReader reader = new XmlTextReader(URLString);
                    //This make an error i dont know why
                    reader.read();

        button.Click += delegate {
            button.Text = string.Format ("{0} clicks!", count++);
        };

    }

````

Note: If i remove Reader.read the code works perfectly .

Please help me .