Ok, I've finally solved the problem. Since I'm using JBoss server, it seems that everything that I put directly on the classpath is overriden by what's in the JBoss client directory especially the hibernate files. So anybody using JBoss, do be careful especially when you are doing the Hibernate Compatibility Matrix portion. Now all I need to know is, since my client is calling my session bean is calling my wrapper datasource which persists the entity to db, where do I place my em.gettransaction.begin(), em.persist(entity), em.gettransaction.commit() and em.gettransaction.rollback() commands? Do I do it in the client as follows :- | BiddingTestBeanRemote bidder= (BiddingTestBeanRemote) ctx.lookup("BiddingTestEAR/BiddingTestBean/remote"); | //BiddingTestBeanLocal bidder = (BiddingTestBeanLocal) PortableRemoteObject.narrow (obj, BiddingTestBean.class); | | em.getTransaction().begin(); | bidder.setBidder(); // call the bean's setter method | em.persist(bidder); | em.getTransaction().commit(); | or in the bean as follows :- | em.getTransaction().begin(); | Bidder bidder = new Bidder(); | bidder.setBidderName("Bidder No 1"); | bidder.setBidSessionId(1); | em.persist(bidder); | em.getTransaction().commit(); | Please can somebody help. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4200312#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...