JBoss 4.0.4 GA, EJB3 RC8

Testing EJB3, Stateless & Statefull examples work, my hypersonic database is configured and working, default datasource configured.

java: Namespace

 +- XAConnectionFactory (class: org.jboss.mq.SpyXAConnectionFactory)
 +- DefaultDS (class: org.jboss.resource.adapter.jdbc.WrapperDataSource)

I'm trying to get an Entity EJB to write something to that datasource but I get the following error:

17:08:46,983 WARN [ServiceController] Problem starting service jboss.j2ee:service=EJB3,module=entity.ejb3
java.lang.RuntimeException: Field private javax.persistence.EntityManager org.jboss.tutorial.entity.bean.ShoppingCartBean.manager @PersistenceUnit in error: EMPTY STRING unitName but there is no deployments in scope

This is my entity bean:

Order.java

@Entity
@Table(name = "PURCHASE_ORDER")
public class Order implements java.io.Serializable {

 private static final long serialVersionUID = 1L;
 private int id;
 private double total;
 private Collection<LineItem> lineItems;


 public Order() {
 super();
 }

 @Id @GeneratedValue(strategy=GenerationType.AUTO)
 public int getId()
 {
 return id;
 }

I use it from a stateless bean that doesn't do much

package slsb;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import entity.*;

import model.Item;

@Stateless
public class SimpleStatelessBean implements SimpleStatelessBeanRemote, SimpleStatelessBeanLocal {

 @PersistenceContext()
 private EntityManager em;

 public Item getItem(Long id) {
 Order o = new Order();
 o.setId(10);
 o.setLineItems(null);
 o.setTotal(100);
 em.persist(o);
 Item item = new Item();
 item.setId(id);
 item.setName("A Java mug");
 return item;
 }
}

I thought it might be due to a missing persistence.xml file but the error is still the same, this is my persistence.xml, but anyway I didn't think you actually needed this (i've seen examples from the Jboss labs working without them, is it really needed?)

<persistence>
 <persistence-unit name="BeanExamples">
 <jta-data-source>java:/DefaultDS</jta-data-source>
 <properties>
 <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
 </properties>
 </persistence-unit>
</persistence>

Any suggestions? Thanks