Problems with draft.mode

I am having some problems using draft.mode. I have a document with
some <remark>...</remark> elements in it. I have checked that my
customisation layer doesn't contain any occurrences of draft.mode or
remark... so any customisations being applied shouldn't be interfering
with the default behaviour. I have grabbed the latest snapshots of the
DocBook stylesheets.

I am converting the document to pdf via fo and using  apache FOP
version 0.95. I am creating two versions. A draft version with:

xsltproc --xinclude --stringparam draft.mode yes --output
UG.xml.draft.fo
/usr/share/docbook-xsl-latest/customisation/fo/custom.xsl UG.xml
fop.bat -d -fo UG.xml.draft.fo -pdf UG.xml.draft.pdf

and a final version with

xsltproc --xinclude --stringparam draft.mode no --output UG.xml.fo
/usr/share/docbook-xsl-latest/customisation/fo/custom.xsl UG.xml
fop.bat -d -fo UG.xml.fo -pdf UG.xml.pdf

The problem is that the remarks are appearing in the final version as
well as the draft version, but I thought that with draft.mode="no"
they weren't supposed to appear.

Anyone got any ideas about what might be going wrong?

Thanks.