Copy checked Rows from one GridView to Another with DropDownList select value using C# in ASP.Net

Hi I want to get data dropdown in gridview. How can I do. I did like below but get blank. 

 private DataTable CheckedData()
        {
            DataTable dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[] { new DataColumn("UrunAd"), new DataColumn("Stok", typeof(int)), new DataColumn("Pozisyon") });
            foreach (GridViewRow rw in example.Rows)
            {
                if (rw.RowType == DataControlRowType.DataRow)
                {
                    CheckBox chk = (CheckBox)rw.Cells[0].FindControl("chcsec");
                    if (chk.Checked)
                    {
                        Label lb = (Label)rw.Cells[1].FindControl("lblUrun");
                        Label lb1 = (Label)rw.Cells[2].FindControl("lblStok");
                        DropDownList drp = (DropDownList)rw.Cells[5].FindControl("drpEleman");
                        dt.Rows.Add(lb.Text, lb1.Text, drp.SelectedItem.Value);
                        
                    }
                 
                }
            }
            return dt;
        }