How to change back color of a particular row in datagrid

private void DevideDuplicate()
        {

            string WID = txtWeaver.Text, QCODE = cbQualityCode.Text; //WID for Worker ID and QCODE is for Quality Code

                foreach (DataGridViewRow row in dgCal.Rows)
                {
                    if (WID == row.Cells[0].Value.ToString() && QCODE == row.Cells[2].Value.ToString())
                    {
                        row.DefaultCellStyle.BackColor = Color.Red;
                    }
                }

        }