dataset with relation

this code not showing any output

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
using System.Web.Configuration;

/* for 2 table display  their must be relation bt table
  one table contain pk & should contain fk. that not present in tables
  so we did it by specify Relation*/

public partial class dataset__with_two_tables : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string connectionstring = WebConfigurationManager.ConnectionStrings["AdventureWorks"].ConnectionString;
            SqlConnection con = new SqlConnection(connectionstring);

            DataSet ds = new DataSet();
            ds.Tables.Add("HumanResources.Employee");
            ds.Tables.Add("HumanResources.EmployeeAddress");
            ds.Tables["HumanResources.Employee"].Columns.Add("EmployeeID");
            ds.Tables["HumanResources.Employee"].Columns.Add("Title");
            ds.Tables["HumanResources.EmployeeAddress"].Columns.Add("EmployeeID");
            ds.Tables["HumanResources.EmployeeAddress"].Columns.Add("ModifiedDate");
            DataRelation dr = new DataRelation("show", ds.Tables["HumanResources.Employee"].Columns["EmployeeID"], ds.Tables["HumanResources.EmployeeAddress"].Columns["EmployeeID"], false);
            //ds.Tables["HumanResources.Employee"].ParentRelations.Add(dr);
            ds.Relations.Add(dr);
            //Retrieving Data from the Relationship

            foreach (DataRow row1 in ds.Tables["HumanResources.Employee"].Rows)
            {
                Response.Write("customertitle:" + row1["Title"].ToString());

                foreach (DataRow row2 in row1.GetChildRows(dr))
                {
                    Response.Write("customer add" + row2["ModifiedDate"].ToString());
                }
            }





          
            GridView4.DataSource = ds.Tables["HumanResources.Employee"];
          //Datagrid1.DataSource= ds.DefaultViewManager;

        } GridView4.DataBind();
    }
}