c# combobox

Merhaba

İl ilçe uygulaması yapmaya çalışıyorum 2 tane comboboxla hata veriyor çözümünü bulamadım.Teşekkürler

using System.Data.SqlClient;

namespace WindowsFormsApplication5
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{

string bag = "Server=SISTEM-PC013;Database=stmm;User Id=sa;Password = P0rtakal; ";
SqlConnection baglanti = new SqlConnection(bag);
baglanti.Open();
SqlCommand komut = new SqlCommand("SELECT il from il ", baglanti);
SqlDataAdapter da = new SqlDataAdapter(komut);
DataTable dt = new DataTable();
da.Fill(dt);
comboBox1.ValueMember = "ıd";
comboBox1.DisplayMember = "il";
comboBox1.DataSource = dt;

baglanti.Close();
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{

string bag = "Server=SISTEM-PC013;Database=stmm;User Id=sa;Password = P0rtakal; ";
SqlConnection baglanti = new SqlConnection(bag);
if (comboBox1.SelectedIndex != -1)
{

baglanti.Open();
SqlCommand komut = new SqlCommand("select * from ile where ile = " + comboBox1.SelectedValue + "", baglanti);
SqlDataAdapter da = new SqlDataAdapter(komut);
DataTable dt = new DataTable();

komut.Fill(dt); <<<<<<<<<<<<<<<<HATA VEREN SATIR>>>>>>>>>>>>>

comboBox2.ValueMember = "ıd";
comboBox2.DisplayMember = "ile";
comboBox2.DataSource = dt;

baglanti.Close();

}