not displaying gridview

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="test.WebForm2" %>

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using Npgsql;

namespace test

{

public partial class WebForm2 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

ddldistrict.AppendDataBoundItems = true;

string sQuery = "SELECT districtna,districtco FROM district";

string sConn = "Server=192.168.1.99;Port=5433;User Id=postgres;Password=user;Database=school;";

DataTable DT = new DataTable();

NpgsqlConnection Conn = new NpgsqlConnection(sConn);

Conn.Open();

DataSet DS = new DataSet("DS1");

NpgsqlDataAdapter DA = new NpgsqlDataAdapter();

DA.SelectCommand = new NpgsqlCommand(sQuery, Conn);

DA.Fill(DS);

ddldistrict.DataTextField = "districtna";

ddldistrict.DataSource = DS;

ddldistrict.DataBind();

Conn.Close();

}

}

protected void ddldistrict_SelectedIndexChanged(object sender, EventArgs e)

{

if (ddldistrict.SelectedIndex == 0)

{

ddltaluk.Enabled = false;

ddltaluk.Items.Clear();

ddltaluk.Items.Insert(0, new ListItem("--Select Taluk--", "-1"));

GridView1.DataSource = null;

GridView1.DataBind();

}

else

{

ddltaluk.Enabled = true;

string sQuery = "SELECT talukname,talukcode FROM taluk";

string sConn = "Server=192.168.1.99;Port=5433;User Id=postgres;Password=user;Database=school;";

NpgsqlConnection Conn = new NpgsqlConnection(sConn);

Conn.Open();

DataSet DS = new DataSet("DS2");

NpgsqlDataAdapter DA = new NpgsqlDataAdapter();

DA.SelectCommand = new NpgsqlCommand(sQuery, Conn);

DA.Fill(DS);

ddltaluk.AppendDataBoundItems = true;

ddltaluk.DataSource = DS;

ddltaluk.DataValueField = "talukname";

ddltaluk.DataTextField = "talukname";

ddltaluk.DataBind();

//GridView1.DataSource = null;

//GridView1.DataSource = DS;

//GridView1.DataBind();

ddltaluk.ClearSelection();

Conn.Close();

}

}

protected void ddltaluk_SelectedIndexChanged(object sender, EventArgs e)

{

string sQuery = "SELECT talukcode,talukname,districtco,statecode,shape_leng,shape_area FROM taluk WHERE talukcode='"+ ddltaluk.SelectedValue +"'";

string sConn = "Server=192.168.1.99;Port=5433;User Id=postgres;Password=user;Database=school;";

NpgsqlConnection Conn = new NpgsqlConnection(sConn);

Conn.Open();

DataSet DS = new DataSet("DS2");

NpgsqlDataAdapter DA = new NpgsqlDataAdapter();

DA.SelectCommand = new NpgsqlCommand(sQuery, Conn);

DA.Fill(DS);

GridView1.DataSource = null;

GridView1.DataSource = DS;

GridView1.DataBind();

Conn.Close();

}

}

}

 

its not displaying grid view. can anybody tell me or help to display.