iTextSharp line separator disappears with PdfPageEventHelper - itext

Question

I'm producing PDF reports using the iTextSharp library. I have a paragraph as title with a line underneath.
When I add an PdfPageEventHelper class as PageEventListener to my writer which handles the background and page numbering on each page, the line disappears. I think it's about the alignment of the background and the line so the line is behind the background but I can't seem to arrange it in front.
Document code:
using (Document doc = new Document())
{
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition", "attachment; filename=IVIPS_report.pdf");
doc.SetPageSize(PageSize.A4.Rotate());
doc.SetMargins(36f, 36f, 36f, 70f);
Response.Cache.SetCacheability(HttpCacheability.NoCache);
bckgr = Image.GetInstance(Request.MapPath(PDF_BACKGROUND_LANDSCAPE_PATH));
bckgr.Alignment = Image.UNDERLYING;
bckgr.SetAbsolutePosition(0, 0);
bckgr.ScaleToFit(doc.PageSize);
PdfWriter writer = PdfWriter.GetInstance(doc, Response.OutputStream);
MyPdfPageEventHelpPageNo PdfPageEvent = new MyPdfPageEventHelpPageNo();
writer.PageEvent = PdfPageEvent;
doc.Open();
Font title = new Font(Font.FontFamily.HELVETICA, 16f, Font.BOLD, BaseColor.DARK_GRAY);
Paragraph p = new Paragraph("Overzicht chauffeurs", title);
p.Alignment = Element.ALIGN_LEFT;
LineSeparator line = new LineSeparator(1f, 100f, BaseColor.DARK_GRAY, Element.ALIGN_CENTER, -27f);
doc.Add(p);
doc.Add(line);
}
PdfPageEvent code:
public class MyPdfPageEventHelpPageNo : iTextSharp.text.pdf.PdfPageEventHelper
{
public override void OnEndPage(PdfWriter writer, Document document)
{
document.Add(bckgr);
Font fFooter = new Font(Font.FontFamily.HELVETICA, 9f, Font.NORMAL, BaseColor.GRAY);
Rectangle page = document.PageSize;
PdfPTable pageFooter = new PdfPTable(1);
pageFooter.TotalWidth = page.Width;
Phrase pagenr = new Phrase("Gegenereerd op " + DateTime.Now.ToString("dd/MM/yyyy") + " - Pagina " + document.PageNumber, fFooter);
PdfPCell c = new PdfPCell(pagenr);
c.Border = Rectangle.NO_BORDER;
c.VerticalAlignment = Element.ALIGN_BOTTOM;
c.HorizontalAlignment = Element.ALIGN_CENTER;
pageFooter.AddCell(c);
pageFooter.WriteSelectedRows(0, -1, 0, 25, writer.DirectContent);
}
}