DOCBOOK: jade+docbook installation : why is only root enabled ?

Hello,

I am trying to install the docbook tools and I do not understand why
only root is enabled to do successfully the tutorial proposed at
http://nis-www.lanl.gov/~rosalia/mydocs/docbook-intro/get-going.html#HELLO-WORLD

curiously, root can do it :

boltz:/home/georgesk/tmp/docbook# jade -d /usr/lib/sgml/stylesheet/dsssl/docbook/cygnus/dbtohtml.dsl -G -t sgml hello.sgml 2>&1 | head

yelds the error message :
jade:/usr/lib/sgml/stylesheet/dsssl/docbook/cygnus/dbtohtml.dsl:1676:21:E: reference to undefined variable "quantity->string"

the work is nearly done.

but an ordinary user cannot :

boltz:~/tmp/docbook$ jade -d /usr/lib/sgml/stylesheet/dsssl/docbook/cygnus/dbtohtml.dsl -G -t sgml hello.sgml 2>&1 | head

yelds a lot of error messages, here are the first lines of them :

jade:hello.sgml:1:59:W: cannot generate system identifier for public text "-//Davenport//DTD DocBook V3.0//EN"
jade:hello.sgml:1:61:E: reference to entity "BOOK" for which no system identifier could be generated
jade:hello.sgml:1:0: entity was defined here
jade:hello.sgml:1:61:E: DTD did not contain element declaration for document type name
jade:hello.sgml:2:6:E: element "BOOK" undefined
jade:hello.sgml:3:12:E: element "BOOKINFO" undefined
jade:hello.sgml:4:10:E: element "DATE" undefined
jade:hello.sgml:5:11:E: element "TITLE" undefined
jade:hello.sgml:6:14:E: element "SUBTITLE" undefined
jade:hello.sgml:8:7:E: element "TOC" undefined

=====================

I tried to enforce some rights, like :

boltz:# chmod -R a+r /usr/lib/sgml

in order to let anyone read the .dsl and .dtd files (this should be
done from the begining). But there is no difference, the ordinary user 
still cannot perform the tutorial.

thanks for any help.

--
Georges Khaznadar.