Merge With Blank Document

Hi all

I have a requirement to merge two pdf documents with a blank page in between. As per API I should be able to achieve this using the following:

pdfEditor.Concatenate(fs1, fs2, fsBlank,  outStream)

where pdfEditor is a instance of PdfFileEditor

fs1 and fs2 are the file streams to merge and fsBlank is the blank page separator. However when executed, I get 0 byte file created.

If on the other hand I use 2 instead of 3 streams (i.e. fs1 and fsBlank or fs1 and fs2) then I get the desired result.

To be clear my requirement is (assuming  p => page)

Pdf1 = p1,p2,p3,p4,p5

Pdf2 = p1,p2,p5

Desired result = new PDF = {Pdf1 + pdf blank + pdf2} = p1,p2,p3,p4,p5,pblank,p7,p8,p9

Any help greatly appreciated.