[JXTA discuss] [error of SimpleJxtaApp exection]

I am learning jxta at first. Now I'm testing simple code of ProgGuideExamples.zip.
But I am frustrated at testing of SimpleJxtaApp.java.
I wonder the cause of the error.
The error shows below in detail...
My test platform is fedora core 3. 
$ java -version
java version "1.4.2"
jdkgcj 0.3.1 (http://www.arklinux.org/projects/jdkgcj)
gcj (GCC) 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE

# ls
SimpleJxtaApp.class  SimpleJxtaApp.java  client  runIt.bat  runit.sh
# ./runit.sh 
Starting JXTA ....
<INFO  2005-07-28 05:40:03,281 NullConfigurator::File) :?> JXTA_HOME = /home/jslim/jxta/ProgGuideExamples/jxta_devguide/HelloWorld/client
<ERROR 2005-07-28 05:40:03,327 NullConfigurator::File) :?> PlatformConfig does not exist
<INFO  2005-07-28 05:40:03,388 NullConfigurator::File) :?> /home/jslim/jxta/ProgGuideExamples/jxta_devguide/HelloWorld/client/jxta.properties already exists
Exception in thread "main" java.lang.ExceptionInInitializerError
   at java.lang.Class.initializeClass() (/usr/lib/libgcj.so.5.0.0)
   at java.lang.Class.isInstance(java.lang.Object) (/usr/lib/libgcj.so.5.0.0)
   at net.jxta.peergroup.PeerGroupFactory.newPlatform() (Unknown Source)
   at net.jxta.peergroup.PeerGroupFactory.newNetPeerGroup() (Unknown Source)
   at SimpleJxtaApp.startJxta() (Unknown Source)
   at SimpleJxtaApp.main(java.lang.String[]) (Unknown Source)
Caused by: java.lang.NullPointerException
   at net.jxta.id.IDFactory.fromURI(java.net.URI) (Unknown Source)
   at net.jxta.id.ID.create(java.net.URI) (Unknown Source)
   at net.jxta.peergroup.PeerGroup.<clinit>() (Unknown Source)
   at java.lang.Class.initializeClass() (/usr/lib/libgcj.so.5.0.0)
   ...5 more
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