[JXTA discuss] Could anybody tell me how to run SimpleJxtaApp?

Hi, I just began to learn JXTA and when I try to run SimpleJxtaApp folling errors ocur:
java.lang.NullPointerException
 at java.io.Reader.<init>(Unknown Source)
 at java.io.InputStreamReader.<init>(Unknown Source)
 at net.jxta.impl.document.LiteXMLDocument.<init>(LiteXMLDocument.java:233)
 at net.jxta.impl.document.LiteXMLDocument$Instantiator.newInstance(LiteXMLDocument.java:146)
 at net.jxta.document.StructuredDocumentFactory.newStructuredDocument(StructuredDocumentFactory.java:518)
 at net.jxta.document.AdvertisementFactory.newAdvertisement(AdvertisementFactory.java:284)
 at SimpleJxtaApp.createConfig(SimpleJxtaApp.java:80)
 at SimpleJxtaApp.startJxta(SimpleJxtaApp.java:98)
 at SimpleJxtaApp.main(SimpleJxtaApp.java:44)
Exception in thread "main" 

The JXTA platform I am using is version 2.3.1, I have include bcprov-jdk14.jar, javax.servlet.jar, jxta.jar, log4j.jar,org.mortbay.jetty.jar into the classpath, but still can not run. And the config interface has not appear too. Could anybody tell me what shall I do? tkx in advance!