Datagrid view is not showing images

while(rdr.Read())
            {
        DataGridViewImageColumn iconColumn = new DataGridViewImageColumn();
                 ImageConverter ic;
                 Image img;
               Byte[] cbyte;
                  ic = new ImageConverter();
                  cbyte = (Byte[])(rdr["Imge"]);
                 img = (Image)ic.ConvertFrom(cbyte);
                Bitmap a = new Bitmap(img);
                 iconColumn.Image = a;
                 iconColumn.Name = "Tree";
                 iconColumn.HeaderText = "Nice tree";
                 dataGridView1.Columns.Insert(0, iconColumn);
            };