DOCBOOK-APPS: PNG notation

Hello docbook specialists,

I am switching (or tying to switch) from docbook 3.0 to 4.1 and from the
modular style sheets 1.44 to 1.69. My backend is jade on UNIX (1.2.1, SP
1.3.3).

When generating e.g. a pdf file, I get the following error messages from
jade:

/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbnotn.mod:84:11:E:
notation "PNG" already defined
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:2805:19:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:2826:19:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:3019:21:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:3060:21:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:3081:21:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:/usr/local/share/sgml/docbook/4.1/dbpool.mod:5004:21:E:
token "PNG" has already occurred in this group
/usr/local/bin/jade:chapter_15510.sgm:13:54:E: end tag for element "GRAPHIC"
which is not open
/usr/local/bin/jade:HAwabsy.sgm:15:283:E: element "DOCINFO" undefined
/usr/local/bin/jade:HAwabsy.sgm:15:6047:E: end tag for element "GRAPHIC"
which is not open

I already searched for the doubled PNG definitions but without success.

Any help is appreciated.

Peter Wunderlich