Вот XML

<ns:RefDemo xmlns:ns="http://jdpa.com/">
<ns:RefDemoRq>
<ID_CR>1234567</ID_CR>
<Serno>01234</Serno>
<GroupCode>2012</GroupCode>
<GUID>aaaAaaAA-bbbb-cccc-dddd-eeeeeeeeeeee</GUID>
<GUIDError/>
</ns:RefDemoRq>
</ns:RefDemo>

Вот определение класса:

[Serializable]
    [XmlRoot(Namespace = "ns", ElementName = "RefDemo")]
    public class RequestMsg
    {
        public class Card 
        {
            [XmlElement("ID_CR")]
            public string IdCR { get; set; }

            [XmlElement("Serno")]
            public string Serno { get; set; }

            [XmlElement("GroupCode")]
            public string GroupCode { get; set; }

            [XmlElement("CRDate")]
            public string CRDateAsString { get; set; }

            [XmlElement("GUID")]
            public string Guid { get; set; }

            [XmlElement("GUIDError")]
            public int? GUIDError { get; set; }
        }

        [XmlElement(Namespace = "ns", ElementName = "RefDemoRq")]
        public Card TheCard { get; set; } = new Card();
    }

При вызове XmlSerializer.Deserialize() получаю

<RefDemo xmlns="http://jdpa.com/"> was not expected

Как заставить XmlSerializer такое превращать в объект?