XML Serialization, how to do

I need to generate the XML in the TISS standard of ANS. I have taken the available schemas in the site / a>, and by xsd2Code generated the classes of tissV3_03_02.

I instantiated an object of type ctm_guiaLote and now I need to generate an XML of that object.

I'm trying to do this:

 XmlSerializer xmlSerializer = new XmlSerializer(typeof(ctm_guiaLote));
 System.IO.Stream stream = new System.IO.FileStream("F:\GuiaTeste.xml", System.IO.FileMode.Create);
 xmlSerializer.Serialize(stream, lote.getlote());
 stream.Close();

I'm having the following exception, among others:

  

Exception: Thrown: "The TISS.ItemChoiceType1 type does not have the 'Item' enumeration value for the 'Item' element of the namespace ''." (System.InvalidOperationException)   The System.InvalidOperationException was thrown: "The TISS.ItemChoiceType1 type does not have the 'Item' enumeration value for the 'Item' element of the namespace ''."   Time: 7/31/2017 12:21:03   Thread: [4416]

And several others like this:

  

"Error while reflecting Type / Property"

     

Exception: Thrown: "Error while reflecting 'Item' property." (System.InvalidOperationException)   A System.InvalidOperationException was thrown: "Error while reflecting 'Item' property."   Time: 7/31/2017 12:21:03   Thread: [4416]

Class ctm_guyLote:

public partial class ctm_guiaLote
{

    private string numeroLoteField;

    private ctm_guiaLoteGuiasTISS guiasTISSField;

    public ctm_guiaLote()
    {
        this.guiasTISSField = new ctm_guiaLoteGuiasTISS();
    }

    public string numeroLote
    {
        get
        {
            return this.numeroLoteField;
        }
        set
        {
            this.numeroLoteField = value;
        }
    }

    public ctm_guiaLoteGuiasTISS guiasTISS
    {
        get
        {
            return this.guiasTISSField;
        }
        set
        {
            this.guiasTISSField = value;
        }
    }
}

class ctm_guiaLoteGuidesTISS:

[XmlInclude(typeof(ctm_spsadtGuia))]
public partial class ctm_guiaLoteGuiasTISS
{

    private List<object> itemsField;

    public ctm_guiaLoteGuiasTISS()
    {
        this.itemsField = new List<object>();
    }

    public List<object> Items
    {
        get
        {
            return this.itemsField;
        }
        set
        {
            this.itemsField = value;
        }
    }
}

GetLote () code:

    public ctm_guiaLote getlote()
    {
        ctm_guiaLote lote = new ctm_guiaLote();
        lote.numeroLote = "1";
        lote.guiasTISS = new ctm_guiaLoteGuiasTISS();

        List<object> guias = new List<object>();

        ctm_spsadtGuia guia = new ctm_spsadtGuia();
        guia.cabecalhoGuia.registroANS = "1";
        guia.cabecalhoGuia.numeroGuiaPrestador = "1";

        guia.dadosAtendimento.indicacaoAcidente = dm_indicadorAcidente.Item0;
        guia.dadosAtendimento.tipoConsulta = dm_tipoConsulta.Item1;

        guia.dadosSolicitacao.caraterAtendimento = dm_caraterAtendimento.Item1;
        guia.dadosSolicitacao.dataSolicitacao = DateTime.Now;
        guia.dadosSolicitacao.indicacaoClinica = "Teste";

        guia.dadosExecutante.CNES = "123";
        guia.dadosExecutante.contratadoExecutante.ItemElementName = ItemChoiceType1.cnpjContratado;
        guia.dadosExecutante.contratadoExecutante.Item = "11111111111111";
        guia.dadosExecutante.contratadoExecutante.nomeContratado = "Contratado";

        guia.dadosSolicitante.contratadoSolicitante.nomeContratado = "Solicitante";
        guia.dadosSolicitante.contratadoSolicitante.ItemElementName = ItemChoiceType1.cpfContratado;
        guia.dadosSolicitante.contratadoSolicitante.Item = "11111111111";

        guia.dadosAutorizacao.dataAutorizacao = DateTime.Now;
        guia.dadosAutorizacao.numeroGuiaOperadora = "2";
        guia.dadosAutorizacao.senha = "54321";

        guia.dadosBeneficiario.atendimentoRN = dm_simNao.N;
        guia.dadosBeneficiario.nomeBeneficiario = "Paciente";
        guia.dadosBeneficiario.numeroCarteira = "9999";
        guia.dadosBeneficiario.numeroCNS = "12345678901234";

        guia.procedimentosExecutados.Add(new ct_procedimentoExecutadoSadt() { dataExecucao = DateTime.Now, procedimento = new ct_procedimentoDados() { codigoProcedimento = "1", codigoTabela= dm_tabela.Item22, descricaoProcedimento = "Consulta" } });

        guias.Add(guia);

        lote.guiasTISS.Items = guias;

        return lote;
    }

Anyone who can help with these exceptions, thank you.