Adobe has extra features beyond the PDF standards. If you have an Adobe-only PDF file (or you have a newer version than someone you're sending the PDF to), you'll be able to open the PDF normally while others will get this message in place of the PDF content:
This seems to be the case especially for PDF forms created in Acrobat Pro that can only be filled out in Acrobat Pro or Acrobat Reader.
To resolve this, the recipient either needs to open the file in the latest version of Adobe Acrobat, or you'll have to print the PDF from Acrobat using a PDF Printer. An additional caveat when using Acrobat on a Mac is that you cannot save a filled-out PDF form using the built-in PDF printer in Acrobat; it will tell you to save as a PDF. The form I had trouble with also was not able to be exported to the PDF/A standard, so the only option I had was to install a 3rd-party PDF printer. If Adobe had used the built-in printing functionality in OS X, we wouldn't even be having this issue.
Install PDFwriter from
http://sourceforge.net/projects/pdfwriterformac/. If you're on Windows, CutePDF and Bullzip PDF Printer are both pretty good. Once you install PDFwriter, go to the Settings app in OS X and open Printers. Click the + at the bottom of the installed printers list to add a new printer, and select PDFwriter from the popup that follows. Now, go back to your PDF in Acrobat, click print, select PDFwriter as the printer, and print it. Your new PDF print file will be located in /users/shared/PDFWriter/. If you want to get fancy, you can also create a link to your dropbox folder by running this command from Terminal:
sudo ln -s /var/spool/pdfwriter/$USER ~/Dropbox/Documents/PDFs
This will upload your print-to-PDF files into your Dropbox.
reference:
http://sourceforge.net/p/pdfwriterformac/discussion/1246009/thread/d66abec3/?limit=25