Hello, ¡I have another problem! I am using jboss 5.0.1 (All server) with EJBs and JPA. When I try to call a service with persistence it returns: "java.lang.NoClassDefFoundError: javax/transaction/Synchronization" I have found where is that class in version 4, but not in version 5. Do you know which jar should I use? Thanks. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4240938#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...