c# Serialize

gistfile1.cs

        public static bool Serialize<T>(this T item, string filename)
        {
            try
            {
                var ser3 = new XmlSerializer(typeof(T));
                using (var writer = XmlWriter.Create(filename))
                {
                    ser3.Serialize(writer, item);
                }
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

Class to be serialized should be with Public access modifier.