Getting started, using FOP/AntennaHouse

Environment:
Windows 2000, Java 1.4.1, FOP 0.20.5rc, AntennaHouse XSL Formatter 2.4,
docbook-xsl-1.60.1

Hello,

I'm trying to use the stylesheets coming with Norman Walsh's
docbook-xsl-1.60.1, by transforming /docsrc/publishing.xml with
/fo/docbook.xsl.
I'm getting rather unspecific errors shortly after the beginning of the
transformation.

Using FOP: java.lang.RuntimeException. java.lang.NullPointerException
Using AntennaHouse: The parameter is incorrect.

I'm able to do other XSL:FO transformations.

Any ideas?
Thanks very much,
Robert