C# XML Deserialization error !!!

namespace XML_Test
{

    class Program
    {
        static void Main(string[] args)
        {
            Test t = new Test();
            t.Foo = "TEST";
            t.Privstring = "Another String";

            XmlSerializer ser = new XmlSerializer(typeof(Test));

            FileStream fs = new FileStream("C:\\Pat\\test.xml", FileMode.OpenOrCreate);

            ser.Serialize(fs,t);

            fs.Close();

            XmlSerializer ser2 = new XmlSerializer(typeof(Test2));

            FileStream instream = new FileStream("C:\\Pat\\test.xml", FileMode.Open);

            //if (ser.Deserialize(instream))
         
                Test2 deserialize = (Test2)ser2.Deserialize(instream);
            

            //Console.Read();

          

        }
    }
    [Serializable]
    public class Test
    {
        public string Foo;
        public string Privstring;
    }
    [Serializable]
    public class Test2
    {
        public string Foo;
        public string Privstring;
    }
}