Display gridview without records

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm10.aspx.cs" Inherits="WebApplication16.WebForm10" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:GridView ID="grdview1" runat ="server" AutoGenerateColumns="false" AllowPaging ="true">
<Columns>
<asp:BoundField DataField ="contactno" HeaderText ="contactno" />
</Columns>
</asp:GridView>
    </div>
    </form>
</body>
</html>


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;

namespace WebApplication16
{
    public partial class WebForm10 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("contactno");
            dt.Rows.Add(new object[] { "" });
            grdview1.DataSource = dt;
            grdview1.DataBind();
        }
    }
}