yunshi tan [https://community.jboss.org/people/yunshi] created the discussion "Re: @PersistenceContext is null in jboss7" To view the discussion, visit: https://community.jboss.org/message/759828#759828 -------------------------------------------------------------- Thanks Wolf-Dieter et Nicklas, Finally find out the probleme. It has nothing to do with Ejb, neither Hibernate, but classloading I think. My probleme is *I have a parent DAO  which was placed in a module* public abstract class ParentDAO{    @PersistenceContext    private EntityManager em;    // some basic functions... } *Then other DAO extends the parent DAO and they are placed in deployment* @Stateless public class DAO extends ParentDAO implements LocalDAO, RemoteDAO{    // other dao functions using em from parentDAO... } After I move the ParentDAO project out to deployment from the module, it works. I cannot really figurer out why but I think its the classloading probleme. -------------------------------------------------------------- Reply to this message by going to Community [https://community.jboss.org/message/759828#759828] Start a new discussion in JBoss AS 7 Development at Community [https://community.jboss.org/choose-container!input.jspa?contentType=1&...]