Getting Exception "document is open" while generating pdf - vb.net

Question

I'm trying to convert tiff file to pdf using iTextSharp library and getting this exception.
"document is open"
Here is my code:
Dim saveFileDialog1 As New SaveFileDialog()
saveFileDialog1.Filter = "Pdf files (*.pdf)|*.pdf|All files (*.*)|*.*"
saveFileDialog1.FilterIndex = 2
saveFileDialog1.RestoreDirectory = True
If saveFileDialog1.ShowDialog() = DialogResult.OK Then
' creation of the document with a certain size and certain margins
Dim document As New iTextSharp.text.Document(iTextSharp.text.PageSize.A4, 0, 0, 0, 0)
' load the tiff image and count the total pages
Dim bm As New System.Drawing.Bitmap(OpenFileDialog1.FileName)
Dim total As Integer = bm.GetFrameCount(System.Drawing.Imaging.FrameDimension.Page)
document.Open()
' creation of the different writers
Dim writer As iTextSharp.text.pdf.PdfWriter = iTextSharp.text.pdf.PdfWriter.GetInstance(document, New System.IO.FileStream(saveFileDialog1.FileName, System.IO.FileMode.Create))
Dim cb As iTextSharp.text.pdf.PdfContentByte = writer.DirectContent
For k As Integer = 0 To total - 1
bm.SelectActiveFrame(System.Drawing.Imaging.FrameDimension.Page, k)
Dim img As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(bm, System.Drawing.Imaging.ImageFormat.Bmp)
' scale the image to fit in the page
img.ScalePercent(72.0F / img.DpiX * 100)
img.SetAbsolutePosition(0, 0)
cb.AddImage(img)
document.NewPage()
Next k
document.Close()
Can anyone say me what and where am I going wrong ?
EDIT:
When I tried to add the dimensions:
img.ScaleToFit(595, 842)
img.SetAbsolutePosition(0, 0)

Answer 1

As I explain in my book about iText, you should create a PDF in 5 steps when using iText(Sharp). Creating the writer is step 2 and opening the document is step 3. You have switched these two steps and this is what causes the error.
You need to move the line document.Open() down a couple of lines. After where you create the writer and before creating the cb instance.