First time using this and ran into a problem right away. Here's what I did:
I'm on a Mac, scanned some student tests at 300dpi, using a Fuji Xerox scanner to a pdf file. Followed these instructions: http://www.formscanner.org/quickstart-guide/convert-pdf
and got the "xx.pdf 0x0x0 : not a picture" result.
What went wrong? Appreciate any help. Thanks.