datagridview中使用combox

private void Form1_Load(object sender, EventArgs e)
{
    sysdt2.Columns.Add("factory", System.Type.GetType("System.String"));
    sysdt2.Rows.Add("一厂");
    sysdt2.Rows.Add("二厂");

}

private void toolStripButton2_Click(object sender, EventArgs e) //新增
{
    DataGridViewComboBoxColumn x1 = new DataGridViewComboBoxColumn();
    x1.DataSource = sysdt2;
    x1.DisplayStyle = DataGridViewComboBoxDisplayStyle.ComboBox;
    x1.HeaderText = "厂别";
    x1.DisplayMember = "factory";
    x1.ValueMember = "factory";
    dataGridView1.Columns.Add(x1);
}