I have two EJB3 subsystem: Auth system: was packed in auth.jar file and Order system: was packed in order.jar file Now, I have a entity bean that's name is EOlocation, and it was packed in auth.jar: @Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class EOlocation implements Serializable { @ManyToOne @JoinColumn(name = "eoaccount_id") private EOaccount account; ..... } Another entity bean is EOorderLocation, it's a subclass for EOlocation, but was packed in order.jar @Entity public class EOorderLocation extends EOlocation { ....... } I am deploy the auth.jar before than deploy the order.jar file. Than I get the exception like the following: 15:15:15,897 WARN [ServiceController] Problem starting service persistence.units:unitName=EatOutDS org.hibernate.AnnotationException: @OneToOne or @ManyToOne on com.tweatout.auth.domain.EOlocation.account references an unknown entity: com.tweatout.auth.domain.EOaccount at org.hibernate.cfg.FkSecondPass.doSecondPas(FkSecondPass.java:40) at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(Annotatio nConfiguration.java:288) at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1034 ) at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.j ava:1015) at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerCo nfigurator.java:154) at org.hibernate.ejb.Ejb3Configuration.createEntityManagerFactory(Ejb3Co How can I implement the reference or inheritance entity bean between two jar files? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3980632#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...