Java SE (Java Platform, Standard Edition)

My program compiles fine, but I get

Exception in thread "Thread-8" java.lang.NoClassDefFoundError: org/jdom/JDOMException

at runtime.

I have the jdom.jar inside WEB-INF/lib of the web project, and also as a referenced library, (and in the manifest) in the program jar.

I (having run out of ideas) also put it in the actual JDK/lib/ext - so it's referenced with cmd> java org.jdom.JDOMException

Exception in thread "main" java.lang.NoSuchMethodError: main

, so is definately there.

Exception in thread "Thread-7" java.lang.NoClassDefFoundError: org/jdom/JDOMException
  // My class that calls "xml.setRootElement(new Element("DATA"));"
	at runtime.PokeTriad.<init>(PokeTriad.java:95)
	at com.sun.jnlp.SingleInstanceServiceImpl$TransferListener.newActivation(Unknown Source)
	at com.sun.deploy.si.SingleInstanceImpl$SingleInstanceServer$2.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.deploy.si.SingleInstanceImpl$SingleInstanceServer.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.jdom.JDOMException
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at com.sun.jnlp.JNLPClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 6 more

I can't see where the JDOMException is coming from. Am I doing something wrong? (I am trying to use a (PersistenceService)ServiceManager.
lookup("javax.jnlp.PersistenceService") to store a persistant XMLDocument.)

Cheers in advance.