jeg får exception ved forbindelse til ejb

Hej,
der opstår en exception, når jeg vil køre min klient, der skal benytte en EJB jeg har på en JBoss server.

Hvorfor kastes exception?


Min klasse:

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.rmi.PortableRemoteObject;


public class VekslerKlient
{

  public static void main(String[] args) {

      try
      {

        System.setProperty("java.naming.factory.initial", "org.jnp.interfaces.NamingContextFactory");
        System.setProperty("java.naming.factory.url.pkgs", "org.jnp.interfaces");
        System.setProperty("java.naming.provider.url", "localhost:1099");

        Context initial = new InitialContext();

        Object objref = initial.lookup("ejb/Veksler");

        VekslerHome home = (VekslerHome)PortableRemoteObject.narrow(objref, VekslerHome.class);

        Veksler veksler = home.create();

        double beloeb;

        beloeb = veksler.euroTilDollar(100);
        System.out.println("100 euro er "+beloeb+" dollar.");

        beloeb = veksler.dollarTilEuro(100);
        System.out.println("100 dollar er "+beloeb+" euro.");

        System.exit(0);

      }
      catch (Exception ex)
      {
        System.err.println("Caught an unexpected exception!");
        ex.printStackTrace();
      }
  }
}

FEJLBESKEDEN ER (udskrift af exception):

Caught an unexpected exception!
javax.naming.NoInitialContextException: Cannot instantiate class: org.jnp.interf
aces.NamingContextFactory [Root exception is java.lang.ClassNotFoundException: o
rg.jnp.interfaces.NamingContextFactory]
        at javax.naming.spi.NamingManager.getInitialContext(Unknown Source)
        at javax.naming.InitialContext.getDefaultInitCtx(Unknown Source)
        at javax.naming.InitialContext.init(Unknown Source)
        at javax.naming.InitialContext.<init>(Unknown Source)
        at VekslerKlient.main(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.jnp.interfaces.NamingContextFac
tory
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at com.sun.naming.internal.VersionHelper12.loadClass(Unknown Source)
        ... 5 more