Thanks for the reply. I thought it was possible that my problem was related to Seam, this is why I posted on the form: I assumed that at some point with the Glassfish example javax.persistence.Persistence.createEntityManagerFactory would be called for database access. Therefore, why should the core:entity-manager-factory component which explicitly calls Persistence.createEntityManagerFactory cause my problems unless the component was incompatible with Glassfish. However, as it is obvious to you that Seam plays no part in my problems and I am one step closer to solving them. Thanks again. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4054976#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...