I have downloaded the PDFviewer.zip file and followed all instructions.
I user Oracle forms 10g.
The forms runs in explorer but pdf file not shown, nor I see the navigation bar.
Tried my level best but no success.
I understand, often people post in old threads not realising that they are old.
I think that it is difficult to understand how to helpp you without more details of what you did (ie which files you changed and how), and what debugging you have then performed to check which parts of the solution are working.