Merlin: log4j provider

I'm trying to switch from logkit to log4j in 3.3.0.

So far all I've done is add a line to merlin.properties:

merlin.logging.implementation = 
artifact:avalon-logging/avalon-logging-log4j#1.0.0


However I get the following error:

using MAVEN_REPO_LOCAL: /home/icejeg/.maven/repository
Starting Merlin 3.3.0.
====================
             Platform: Linux
            Java Home: /usr/local/j2sdk1.4.2
          Merlin Home: /usr/local/merlin
      Security policy: /usr/local/merlin/bin/security.policy
          JVM Options: -Xdebug 
-Xrunjdwp:transport=dt_socket,address=9000,server=y,suspend=n 
-Dorg.xml.sax.driver=org.apache.xerces.parsers.SAXParser
        Bootstrap JAR: 
/usr/local/merlin/system/merlin/jars/merlin-cli-3.3.0.jar
     Merlin Arguments:  -system "/home/icejeg/.maven/repository" 
-repository "/home/icejeg/.maven/repository"

---- runtime exception report 
--------------------------------------------------
Exception: java.lang.NullPointerException
Message: null
---- stack trace 
---------------------------------------------------------------
java.lang.NullPointerException
org.apache.avalon.logging.log4j.Log4JLoggingFactory.configure(Log4JLoggingFactory.java:156)
org.apache.avalon.logging.log4j.Log4JLoggingFactory.create(Log4JLoggingFactory.java:146)
org.apache.avalon.merlin.impl.DefaultFactory.createLoggingManager(DefaultFactory.java:578)
org.apache.avalon.merlin.impl.DefaultFactory.create(DefaultFactory.java:188)
org.apache.avalon.merlin.cli.Main.<init>(Main.java:301)
org.apache.avalon.merlin.cli.Main.main(Main.java:255)
--------------------------------------------------------------------------------

xargs: /usr/local/j2sdk1.4.2/bin/java: exited with status 255; aborting



Anyone have any wisdom?

thanks,

-- 
Jon Elson-Green