Hi, I have two Entities A and B each with a simple primary key idA and idB. I join them using a third table AB that has a composite primary key using an embedded primary key class ABPk. So far it works fine. Now I got another table C with a simple primary key idC involved that has to be joined with AB using another table ABC. So this last table has a composite primary key ABCpk that consists of the parts idC and ABPk which itself consists of idA and idB. All composite primary keys use the @Embeddable Annotation and are imbedded using @EmbeddedId similar to what is recommended in https://www.jboss.org/community/wiki/EJB3relationships My problem is that on ABC I can't activate the @ManyToOne Annotation that references AB. On deployment this gives me a NullPointerException. I am using JBoss 4.2.3.GA with Sun Java 1.6.0.16. Thanks Martin View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4261780#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...