Cannot set filename when scanning with hp-scan from ADF

I wanted to write me a little script that scans from ADF using the tool hp-scan.

Therefore I execute "hp-scan --adf -sfile -otest"
Then I get the error "warning: File destination enabled with no output file specified." and it scans to the default filename.

Then I tried "hp-scan --adf -sfile -otest.pdf" (with pdf extension)
This gives me the error "error: Only JPG (.jpg) and PNG (.png) output files are supported."

Last try: "hp-scan --adf -sfile -otest.jpg"
Error: "error: ADF scans must be saved in PDF file format."

Whatever I try, I cannot set the filename.
I use openSUSE 12.3 and upgraded hplip to the latest version "HP Linux Imaging and Printing System (ver. 3.13.4)"