Problems merging pdf files on version 1.3

[antoniotr]

Hi:

I get some errors trying to merge PDF files on version 1.3 (.NET)
Some properties throw exception:
'file.Document.PageSize' threw an exception of type 'System.NullReferenceException'
'file.Document.Resources' threw an exception of type 'System.NullReferenceException'

But the problem comes with:
'fil.Document.Pages.Count' threw an exception of type 'System.NullReferenceException'

On PageManager(pdfdoc).Add(file.Document);

I get

" at org.pdfclown.documents.Pages.get_Count()\r\n at org.pdfclown.documents.Document.IncludeT\r\n
at org.pdfclown.tools.PageManager.Add(Document document)\r\n "

I've tried to fix this with some workarounds but I haven't been able.
What could I do to fix this?

Thank you!