WinApp C# ระบุค่า checkbox ใน dataGridView ไม่ได้ครับ

void SetData()
        {
            
                this.toolStripStatusLabel1.Text = "Runing...";
            
            if (string.IsNullOrEmpty(textBox1.Text)) return;
            System.Data.DataTable dt = new System.Data.DataTable();
            dt.Columns.Add(new System.Data.DataColumn("Filename", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Path", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Size", typeof(double)));
            dt.Columns.Add(new System.Data.DataColumn("Modified", typeof(DateTime)));
            dt.Columns.Add(new System.Data.DataColumn("MD5", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Select", typeof(bool)));

            System.IO.Directory.GetFiles(this.textBox1.Text, "*.*", System.IO.SearchOption.AllDirectories).ToList<string>()
                .ForEach(f =>
                {
                    DataRow dr = dt.NewRow();
                    dr["Filename"] = System.IO.Path.GetFileName(f);
                    dr["Path"] = System.IO.Path.GetDirectoryName(f);
                    dr["Size"] = new System.IO.FileInfo(f).Length;
                    dr["Modified"] = new System.IO.FileInfo(f).LastAccessTime;
                    dr["MD5"] = GetMD5HashFromFile(f);
                    dr["Select"] = false;
                    dt.Rows.Add(dr);
                    this.toolStripStatusLabel1.Text = "Add File:" + f;
                });

            dataGridView1.Invoke(new Action(() =>
            {
                dataGridView1.DataSource = dt;
                dataGridView1.Columns[0].Width = 250;
                dataGridView1.Columns[1].Width = 450;
                dataGridView1.Columns[4].Width = 250;
                dataGridView1.Sort(dataGridView1.Columns[4], ListSortDirection.Ascending);
            }));
            
                this.toolStripStatusLabel1.Text = "Complete";
            
        }

private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
        {
            Color cl = Color.LightGoldenrodYellow;
     

            string cri = "";
            try
            {
                for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)
                {
                    
                        if (dataGridView1[4, i].Value.ToString() != cri)
                        {
                            cri = dataGridView1[4, i].Value.ToString();
                            cl = (cl != Color.LightGoldenrodYellow) ? Color.LightGoldenrodYellow : Color.LightCyan;
                        }
                        else
                        {
                          // dataGridView1[5, i].Value = true;
                        }

                    dataGridView1.Rows[i].DefaultCellStyle.BackColor = cl;

                   


                }
            }
            catch { }
           
        }