List 3 Layers c # SQL SERVER Window Form

Good morning. I'm doing a form that is to register a user I'm doing it in the c # language with 3 layers and SQL SERVER database.

In my Registration form I have this aspect as the image:

As you can see in my form I have 5 combobox. The problem is that I want that combobox to be shown dynamically with a procedure.

This is the procedure I use to show my procedure

Create procedure listarviaincidencia

@opt int,

as

if @opt =1

begin

SELECT DerivarA =   REPLICATE('0',2 - LTRIM(RTRIM(LEN(DerivarID)))) + LTRIM(RTRIM(CAST(DerivarID AS CHAR(2)))) + ' - ' +
                                UPPER(CAST(DerivarA AS VARCHAR(150)))
        FROM TAteDerivarA
        ORDER BY DerivarID

end

This is the code of my layers:

Data Layer:

public class Cls_Conexion
{
    SqlConnection conexion = new SqlConnection("Data Source=192.168.105.150\SQL2012;Initial Catalog=DBProAuxQP;User Id=sa;Password=DBServ@14;");

    //Metodo para abrir la conexion

    void abrir_conexion()
    {
        if (conexion.State == ConnectionState.Closed)
        {
            conexion.Open();
        }
    }

    //Cerrar la Conexion 

    void cerrar_conexion()
    {
        if (conexion.State == ConnectionState.Open)
        {
            conexion.Close();
        }
    }

    //Metodo para ejecutar los Procedimientos  (Insert,delete,Update)

    public void Ejecutar_sp(String NombreSp, List<Cls_Parametro> lst)
    {
        SqlCommand  cmd;

        try
        {
            abrir_conexion();
            cmd = new SqlCommand(NombreSp,conexion);
            cmd.CommandType = CommandType.StoredProcedure;
            if (lst != null)
            {
                for (int i = 0; i < lst.Count; i++)
                { 
                    //Verificar el Tipo de Entrada
                    if (lst[i].Direccion == ParameterDirection.Input)
                    {
                        cmd.Parameters.AddWithValue(lst[i].Nombre, lst[i].Valor);
                    }

                    //Verificando el Tipo de Salida
                    if (lst[i].Direccion == ParameterDirection.Output)
                    {
                        cmd.Parameters.Add(lst[i].Nombre, lst[i].TipoDato, lst[i].Tamaño).Direction = ParameterDirection.Output;
                    }

                }
                cmd.ExecuteNonQuery();

                //Recuperando los valores de Salida

                for (int i = 0; i < lst.Count; i++)
                {
                    if (cmd.Parameters[i].Direction == ParameterDirection.Output)
                    {
                        lst[i].Valor = cmd.Parameters[i].Value.ToString();
                    }
                }
            }


        }
        catch (Exception ex)
        {
            throw ex;
        }
        cerrar_conexion();
    }

    public DataTable Listado(String Nombresp, List<Cls_Parametro> lst)
    {
        DataTable dt = new DataTable();
        SqlDataAdapter da;
        try
        {
            da = new SqlDataAdapter(Nombresp, conexion);
            da.SelectCommand.CommandType = CommandType.StoredProcedure;

            if (lst != null)
            { 
                for(int i=0; i<lst.Count;i++)
                {
                    da.SelectCommand.Parameters.AddWithValue(lst[i].Nombre, lst[i].Valor);
                }
            }
            da.Fill(dt);

        }
        catch (Exception ex)
        {
            throw ex;
        }
        return dt;
    }
}

My business layer:

public class Cls_RegistrarIncidencia
{



    /* Variables para Combobox ViaIncidencia */

    public int VI_Ope { get; set; }
    public string VI_Buscar { get; set; }

    Cls_Conexion M = new Cls_Conexion();



    public DataTable ListadoViaIncidencia()
    {

        List<Cls_Parametro> lst = new List<Cls_Parametro>();
        try
        {
            return M.Listado("PE_Ate_InformacionAtencion_New", lst);
        }
        catch (Exception ex)
        {
            throw ex;
        }

    }
}

My Layer Presentation in the LOAD where I want that combobox to store the data

private void Form1_Load(object sender, EventArgs e)
    {

       RI.VI_Ope = 6;
        RI.VI_Buscar = "";



     DataTable dt =  RI.ListadoViaIncidencia();
     CboViaIncidencia.DataSource = dt;
    }

Show me this error:

But when I execute I get an error in the dt. I would like you to help me I am new to c # I do not know if this is the right way to do it in 3 layers.