XmlSerializer.serialize() creates only header

Question

When I'm trying to serialize my list of customers i get file

<?xml version="1.0"?>
<Customers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" />

No exception thrown. I'm pretty sure it was already working, but i probably changed something somewhere and now I have no idea why it's not working anymore.

I have class CustomerList

[XmlRoot("Customers")]
[XmlInclude(typeof(Customer))]
public class CustomerList
{
    [XmlArray("CustomerList")]
    [XmlArrayItem("Customer")]
    private List<Customer> Customers = new List<Customer>();
    private int position = -1;
...;
}

which does contain items of customer class

[XmlType("Customer")]
public class Customer
{
    private string name = string.Empty;
    private string surname = string.Empty;
    private string phone = string.Empty;
    private string email = string.Empty;

    [XmlElement("Name")]
    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    [XmlElement("Surname")]
    public string Surname
    {
        get { return surname; }
        set { surname = value; }
    }

    [XmlElement("Phone")]
    public string Phone
    {
        get { return phone; }
        set { phone = value; }
    }

    [XmlElement("Email")]
    public string Email
    {
        get { return email; }
        set { email= value; }
    }
...;
}

And this is serialized with

private static Type[] extra = { typeof(Customer) };
private XmlSerializer serializer = new XmlSerializer(typeof(CustomerList), extra);

public void Serialize(CustomerList Customers)
{
    System.IO.FileStream fs = new System.IO.FileStream(filename, System.IO.FileMode.Create);
    serializer.Serialize(fs, Customers);
    fs.Close();
}

Answer 1

Your variables are all private. XmlSerializer can only serialize public properties and fields. From the documentation:

XML serialization is the process of converting an object's public properties and fields to a serial format (in this case, XML) for storage or transport.

and later:

To control the generated XML, you can apply special attributes to classes and members. For example, to specify a different XML element name, apply an XmlElementAttribute to a public field or property, and set the ElementName property.

I suggest that you convert your private fields into public properties (not public fields).