How to customize the group caption text in WinForms GridGroupingControl?

void gridGroupingControl1_QueryCellStyleInfo(object sender, GridTableCellStyleInfoEventArgs e)
{
     if (e.TableCellIdentity.TableCellType == GridTableCellType.GroupCaptionCell && e.TableCellIdentity.GroupedColumn != null)
     {
          GridCaptionRow captionRow = e.TableCellIdentity.DisplayElement as GridCaptionRow;
          string date = "";
          DateTime dt;
          if (e.Style.Text != null && DateTime.TryParse(e.Style.Text.Substring(e.Style.Text.IndexOf(":") + 1, 8), out dt))
          {
                date = dt.ToString("MMM-yyyy");
          }
          e.Style.CellValue = String.Format("{0}: {1} Items.", date,            e.TableCellIdentity.DisplayElement.ParentGroup.GetChildCount());
     }
}

Private Sub gridGroupingControl1_QueryCellStyleInfo(ByVal sender As Object, ByVal e As GridTableCellStyleInfoEventArgs)
     If e.TableCellIdentity.TableCellType = GridTableCellType.GroupCaptionCell AndAlso e.TableCellIdentity.GroupedColumn IsNot Nothing Then
        Dim captionRow As GridCaptionRow = TryCast(e.TableCellIdentity.DisplayElement, GridCaptionRow)
        Dim [date] As String = ""
        Dim dt As DateTime
        If e.Style.Text IsNot Nothing AndAlso DateTime.TryParse(e.Style.Text.Substring(e.Style.Text.IndexOf(":") + 1, 8), dt) Then
            [date] = dt.ToString("MMM-yyyy")
        End If
        e.Style.CellValue = [String].Format("{0}: {1} Items.", [date], e.TableCellIdentity.DisplayElement.ParentGroup.GetChildCount())
     End If
End Sub