XML : How to use `chunk.quietly` in docbook?

I am trying to reduce the verbosity of my XSL transformation, following the documented chunk.quietly (and also here). However this is still failing for me:

  $ /usr/bin/xsltproc  --stringparam chunk.quietly 1 man/gdcmdiff.xml  Note: Writing gdcmdiff.1    

The gdcmdiff.xml is a simple refentry man page:

  $ head -4 man/gdcmdiff.xml  <?xml version='1.0' encoding='UTF-8' standalone='no'?>  <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl-ns/current/manpages/docbook.xsl" ?>  <refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xmlns:xlink="http://www.w3.org/1999/xlink">  <info>