Visual CSharp .NET - Mostrar consulta por filtro de Sql server desde C#

ALTER PROCEDURE [dbo].[Liquidacion__List_Get]

	-- Add the parameters for the stored procedure here

	@anio varchar(4),

	@mes varchar(32),

	@Codigo varchar(18)

AS

    -- Insert statements for procedure here

	SELECT Codigo,Identificacion,Nombre,NIC,Fecha,CodigoServicio,valor from Liquidacion

	group by Codigo, Identificacion, Nombre,year(Fecha),month(Fecha),NIC,Fecha,CodigoServicio,valor

	having year(Fecha)=@anio and month(fecha)=@mes and Codigo=@Codigo

using System;

using System.Collections.Generic;

using System.Configuration;

using System.Data;

using System.Data.SqlClient;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CrudPruebaBD

{

    public class cDatos

    {

        string connectionString = ConfigurationManager.ConnectionStrings["Database"].ConnectionString;

        public DataSet PALiquidacion__List_Get(string anio, string mes, string codigo)

        {

            //Objeto Dataset

            try

            {

                DataSet datos = new DataSet();

                //Objeto Conexion

                SqlConnection connexion = new SqlConnection();

                //Objeto comnand

                SqlCommand command = new SqlCommand();

                SqlDataAdapter da = new SqlDataAdapter();

                connexion.ConnectionString = connectionString;

                command.Connection = connexion;

                command.CommandText = "Liquidacion__List_Get";

                command.Parameters.Add("@anio", SqlDbType.VarChar).Value = anio;

                command.Parameters.Add("@mes", SqlDbType.VarChar).Value = mes;

                command.Parameters.Add("@Codigo", SqlDbType.VarChar).Value = codigo;

                command.CommandType = CommandType.StoredProcedure;

                da.SelectCommand = command;

                da.Fill(datos);

                command.Connection.Close();

                command.Connection.Dispose();

                return datos;

            }

            catch (Exception e)

            {

                //Console.WriteLine("{0} Second exception caught.", e);

                return null;

            }

        }

    }

}

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

  <connectionStrings>

    <add name="Database" connectionString="Data Source=ABSRVWAS95;initial catalog=PruebaDB;persist security info=True; Integrated Security=SSPI;" providerName="System.Data.SqlClient"/>

  </connectionStrings>

    <startup>

        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />

    </startup>

</configuration>

cDatos objdatos = new cDatos();

dtgViews.DataSource = objdatos.PALiquidacion__List_Get(cboanio.Text,cbomes.Text,txtCodigo.Text).Tables[0];