Exception avec Jboss server

Lors de déploiement d'une application avec JBoss sever 4.2.
j'ai l'exception suivante :

Code:

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2010-10-21 12:06:48,500 INFO  [org.hibernate.ejb.Ejb3Configuration] found EJB3 Entity bean: tn.test.stock.entity.Video
2010-10-21 12:06:48,781 DEBUG [org.jboss.ejb3.ServiceDelegateWrapper] Starting failed persistence.units:ear=stock-ear.ear,unitName=stock
javax.persistence.PersistenceException: [PersistenceUnit: stock] class or package not found
	at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1089)
	at org.hibernate.ejb.Ejb3Configuration.addClassesToSessionFactory(Ejb3Configuration.java:886)
	at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:772)
	at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:407)
	at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:126)
	at org.jboss.ejb3.entity.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:246)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.jboss.ejb3.ServiceDelegateWrapper.startService(ServiceDelegateWrapper.java:103)
	at

Est ce quelqu'un peut m'aider sur la nature du problème?