I made a "lpr -P Virtual_PDF_Printer file.txt", then
no errors happens.
the job in the cups-browser show has a state "completed" which is new (before, by printing out of leafpad it had the status "stopped, empty print file!").
I was searching the pdf file in home/temp: nothing is there.
(I modified cups-pdf.conf from "Out /var/spool/cups-pdf/${USER}" in "Out ${HOME}/temp" so, I was expecting to see the file in /home/tmp).