How to deserialize a given xml document

Question

Help figure out why my method Deserialize from the class XML return null, why? Document format attached........................................................ ................................................................................ ................................................................................

public class XMl
{
    //список данных из xml

    public XMl() { }

    public dataroot Deserialize(String pathToFile)
    {
        //dataroot dataRoot = null;

        //var serializer = new XmlSerializer(typeof(dataroot));

        //var reader = new StreamReader(pathToFile);
        //dataRoot = (dataroot)serializer.Deserialize(reader);
        //reader.Close();

        //return dataRoot;

        XmlSerializer ser = new XmlSerializer(typeof(dataroot));
        dataroot dataRoot = null;
        using (XmlReader reader = XmlReader.Create(pathToFile))
        {
            dataRoot = (dataroot)ser.Deserialize(reader);
        }

        return dataRoot;
    }
}


[Serializable()]
public class XML_Vozdykhoobmen
{
    [XmlElement("ID_Zdan")]
    public String ID_Zdan { get; set; }

    [XmlElement("ID_Pom")]
    public String ID_Pom { get; set; }

    [XmlElement("NaimZdaniya")]
    public String NaimZdaniya { get; set; }

    [XmlElement("NaimPomeshcheniya")]
    public String NaimPomeshcheniya { get; set; }

    [XmlElement("KlimatPoyas")]
    public String KlimatPoyas { get; set; }

    [XmlElement("Temperatyra")]
    public String Temperatyra { get; set; }

    [XmlElement("PritokKratnost")]
    public String PritokKratnost { get; set; }

    [XmlElement("PritokEdinitsaIzm")]
    public String PritokEdinitsaIzm { get; set; }

    [XmlElement("VytyazhkaKratnost")]
    public String VytyazhkaKratnost { get; set; }

    [XmlElement("VytyazhkaEdinitsaIzm")]
    public String VytyazhkaEdinitsaIzm { get; set; }

    [XmlElement("EdinitsaIzm")]
    public String EdinitsaIzm { get; set; }

    [XmlElement("PoRaschety")]
    public String PoRaschety { get; set; }

    [XmlElement("Kolichestvo")]
    public String Kolichestvo { get; set; }

    [XmlElement("Prim")]
    public String Prim { get; set; }
}

[Serializable()]
[XmlRoot("dataroot")]
public class dataroot
{
    //[XmlArray("Vozdykhoobmens")]
    [XmlArrayItem("XML_Vozdykhoobmen", typeof(XML_Vozdykhoobmen))]
    public XML_Vozdykhoobmen[] Vozdykhoobmen { get; set; }
}