InvalidOperationException when Serializing

Question

I get an InvalidOperationException when trying to reflect the "listing" property, as said by inner exception. When it tries to serialize ArmyListing.

All the variables are public. Checked List can be serialized. Most errors I found where with people using Dictionaries which can't.

Any idea why it appears not to be serializable?

//[Serializable]
public class ArmyListing
{

    [XmlElement("army")]
    public List<Army> listing { get; set; }

    public void SerializeToXML(ArmyListing armyListing)
    {
        try
        {
            XmlSerializer serializer = new XmlSerializer(typeof(ArmyListing));
            TextWriter textWriter = new StreamWriter(@"C:\Test\40k.xml");
            serializer.Serialize(textWriter, armyListing);
            textWriter.Close();
        }
        catch (Exception ex) { }
    }
}

//[Serializable]
public class Army
{
    //public Army();

    [XmlAttribute]
    [XmlArray("unit-category")]
    public List<UnitCategory> settingconstraints { get; set; }
    [XmlAttribute("name")]
    public string armyName { get; set; }
}

//[Serializable]
public class UnitCategory
{
    //public UnitCategory();

    [XmlArray("unit-type")]
    public List<UnitType> setting { get; set; }
    [XmlAttribute("name")]
    public string unitCategoryName { get; set; }
}

//[Serializable]
public class UnitType
{
    //public UnitType();

    [XmlArray("unit")]
    public List<Unit> setting { get; set; }
    [XmlAttribute("name")]
    public string unitTypeName { get; set; }
}

//[Serializable]
public class Unit
{
    //public Unit();

    [XmlAttribute("name")]
    public string unitName { get; set; }
    [XmlAttribute("composition")]
    public string compsition { get; set; }
    [XmlAttribute("weapon-skill")]
    public string weaponSkill { get; set; }
    [XmlAttribute("ballistic-skill")]
    public string ballisticSkill { get; set; }
    [XmlAttribute("strength")]
    public string strength { get; set; }
    [XmlAttribute("toughness")]
    public string T { get; set; }
    [XmlAttribute("wounds")]
    public string wounds { get; set; }
    [XmlAttribute("initiative")]
    public string initiative { get; set; }
    [XmlAttribute("attacks")]
    public string attacks { get; set; }
    [XmlAttribute("leadership")]
    public string leadership { get; set; }
    [XmlAttribute("saving-throw")]
    public string saveThrow { get; set; }
    [XmlAttribute("armour")]
    public string armour { get; set; }
    [XmlAttribute("weapons")]
    public string weapons { get; set; }
    [XmlAttribute("special-rules")]
    public string specialRules { get; set; }
    [XmlAttribute("dedicated-transport")]
    public string dedicatedTransport { get; set; }
    [XmlAttribute("options")]
    public string options { get; set; }
}

 //Form
namespace ThereIsOnlyRules
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        ArmyListing armyListing = new ArmyListing();
        armyListing.SerializeToXML(armyListing);
    }
}
}

Answer 1

This is the part that doesn't work:

[XmlAttribute]
[XmlArray("unit-category")]

[XmlArray] & [XmlAttribute] can't both be defined on the same property.

If you keep drilling into .InnerException until you get to the original problem, the serializer even tells you this:

There was an error reflecting type 'ArmyListing'.
There was an error reflecting property 'listing'.
There was an error reflecting type 'Army'.
There was an error reflecting property 'settingconstraints'.
XmlAttribute and XmlAnyAttribute cannot be used in conjunction with XmlElement, XmlText, XmlAnyElement, XmlArray, or XmlArrayItem.