Event in ComboBox inside a Datagridview

I have a form where the header and detail of a Purchase Order exists. In the Load, load the detail data in a DataGridView with the CargarDetalle() method correctly.

My problem is that when I select an item of ComboBox , this event is not immediately recognized in the method CellValueChanged of DataGridView , as if the combo did not belong to it and does not update the other fields ( puniot and ptotal ) BUT when I then click on any other cell, YES it does ...

How can I generate the% com_com% share event mentioned?

    private void CargarDetalle()
    {
        dgvDetOC.Rows.Clear();
        if (TxtId.Text.Length > 0)  // es invisible. Solo se visualiza el Codigo correaltivo
        {
            oListaOrdencompras = oOrdencompra.GetAll();
            foreach (ordencompra orden in oListaOrdencompras)
            {
                if (orden.id == Convert.ToInt32(TxtId.Text))
                {
                    int i = 0;
                    foreach (det_ordencompra item in orden.det_ordencompras)
                    {
                        dgvDetOC.Rows.Add();
                        dgvDetOC.Rows[i].Cells[0].Value = item.id.ToString();   // col invisible
                        // En tiempo de Diseño se hacen estas dos cossas:
                        // Nombre de la celda donde está el combo: Unidad
                        // DataPropertyName: IdUnidad
                        DataGridViewComboBoxColumn CmbDetalle = dgvDetOC.Columns["Articulo"] as DataGridViewComboBoxColumn;
                        CmbDetalle.DataSource = oOrdenarArticulos;
                        CmbDetalle.DisplayMember = "nombre";
                        CmbDetalle.ValueMember = "id";
                        dgvDetOC.Rows[i].Cells[1].Value = item.idarticulo;
                        //
                        dgvDetOC.Rows[i].Cells[2].Value = item.punit;
                        dgvDetOC.Rows[i].Cells[3].Value = item.cantidad;
                        dgvDetOC.Rows[i].Cells[4].Value = item.ptotal;
                        dgvDetOC.Rows[i].Cells[5].Value = item.idordencompra.ToString();    // col invisible
                        i = i + 1;
                    }
                    break;
                }
            }
        }
    }



private void dgvDetOC_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            if (dgvDetOC.RowCount > 0)
            {
                try
                {
                    // Al cambiar el Articulo en el combo
                    if (dgvDetOC.Columns[e.ColumnIndex].Name == "Articulo")
                    {
                        int IdArtic = Convert.ToInt32(dgvDetOC.Rows[e.RowIndex].Cells[1].Value);
                        articulo eArticulo = new articulo();
                        eArticulo = oArticulo.GetById(IdArtic);
                        if (eArticulo != null)
                        {
                            // Calculamos el nuevo punit y ptotal ---- ptotal = punit * cantidad
                            // Aqui la cantidad no varía
                            dgvDetOC.Rows[e.RowIndex].Cells[2].Value = eArticulo.pbruto;    // punit
                            dgvDetOC.Rows[e.RowIndex].Cells[4].Value = Convert.ToDecimal(dgvDetOC.Rows[e.RowIndex].Cells[2].Value) * Convert.ToDecimal(dgvDetOC.Rows[e.RowIndex].Cells[3].Value);   // ptotal
                            //dgvDetOC.CurrentCell = dgvDetOC.Rows[e.RowIndex].Cells[3];
                            //DtpFechaEmision.Focus();
                        }
                    }
                    // P.Unit o Cantidad
                    if (dgvDetOC.Columns[e.ColumnIndex].Name == "punit" || dgvDetOC.Columns[e.ColumnIndex].Name == "cantidad")
                    {
                        // ptotal = punit * cantidad
                        dgvDetOC.Rows[e.RowIndex].Cells[4].Value = Convert.ToDecimal(dgvDetOC.Rows[e.RowIndex].Cells[2].Value) * Convert.ToDecimal(dgvDetOC.Rows[e.RowIndex].Cells[3].Value);
                    }
                    // Totalizamos los montos de la OC
                    decimal TotalOrden = 0;
                    for (int i = 0; i <= dgvDetOC.RowCount - 1; i++)
                    {
                        TotalOrden = TotalOrden + Convert.ToDecimal(dgvDetOC.Rows[i].Cells[4].Value);  // ptotal
                    }
                    TxtVventa.Text = string.Format("{0:N2}", TotalOrden / (1 + Convert.ToDecimal(TxtPorcIgv.Text)));
                    TxtMtoIgv.Text = string.Format("{0:N2}", TotalOrden - Convert.ToDecimal(TxtVventa.Text));
                    TxtMonto.Text = string.Format("{0:N2}", TotalOrden);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "Ingreso de Ítems", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }