Documentation not building?

Hi all,

php-gtk-doc suddenly doesn't build for me; I did this on a fresh checkout:

> anant@theghost ~/php/build/php-gtk-doc $ autoconf
> anant@theghost ~/php/build/php-gtk-doc $ ./configure 
> checking for xsltproc... /usr/bin/xsltproc
> checking for php... /usr/bin/php
> checking for language... en (default)
> checking whether to build silently... no
> configure: creating ./config.status
> config.status: creating Makefile
> config.status: creating ./scripts/manual.xml
> config.status: creating ./scripts/mtoc.xml
> config.status: creating ./scripts/testmanual.xml
> config.status: creating ./stylesheets/html/chunk.xsl
> config.status: creating ./stylesheets/html/phpweb.xsl
> config.status: creating ./stylesheets/html/updates.xsl
> config.status: creating ./scripts/genchapterents.php
> creating chapters.ent
> creating name_to_id.xsl
> anant@theghost ~/php/build/php-gtk-doc $ make
> /usr/bin/xsltproc --param base.dir "'build/en/html/'" --xinclude ./stylesheets/html/chunk.xsl ./scripts/manual.xml 
> Writing build/en/html/copyright.html for legalnotice
> Writing build/en/html/preface.html for book
> Writing build/en/html/tutorials.installation.windows.html for sect1
> Writing build/en/html/tutorials.installation.linux.html for sect1
> Writing build/en/html/tutorials.installation.macosx.html for sect1
> Writing build/en/html/tutorials.installation.macosx-stepbystep.html for sect1
> Writing build/en/html/tutorials.installation.html for chapter
> runtime error: file stylesheets/html/name_to_id.xsl line 52 element choose
> Variable 'class' has not been declared.
> make: *** [build/en/html/index.html] Error 10

I am puzzled, this used to work only a week ago. Any ideas as to what 
the problem might be? (I suspect there is something wrong with my 
xsltproc or docbook stylesheets; because it seems to be building fine 
for others)

Thanks & Regards,
--
Anant