J2EE - JPA - EJB3 - Transactions in MDB methods

I have resource local datasource (Oracle9i) deployed at JBoss 5.1.0:

<datasources>
  <local-tx-datasource>
    <jndi-name>OracleDS</jndi-name>
    <connection-url>jdbc:oracle:thin:@IP_ADDRESS:1521:inv9i</connection-url>
    <driver-class>oracle.jdbc.driver.OracleDriver</driver-class>
    <user-name>***</user-name>
    <password>***</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter</exception-sorter-class-name>
    <metadata>
        <type-mapping>Oracle9i</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>

persistence unit:

<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="myEJB" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <non-jta-data-source>java:OracleDS</non-jta-data-source>
        <class>hr.bel.model.Instrument</class>
        <class>hr.bel.model.Order</class>
        <class>hr.bel.model.OrderAdditionalData</class>
        <class>hr.bel.model.OrderCondition</class>
        <class>hr.bel.model.Trade</class>
        <class>hr.bel.model.TradeAdditionalData</class>
        <class>hr.bel.model.Tradeticker</class>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle9iDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="none" />
            <property name="hibernate.show_sql" value="true" />
        </properties>
    </persistence-unit>
</persistence>

Within an MDB, when onMessage method is invoked I'm trying to persist an bean and fetch latest 5 beans of that type via an namedQuery:

@PersistenceContext
    EntityManager em = null;
    public void onMessage(MyMessage msg) {
        Map message = msg.getMessageTree(false);
        Instrument instrument = em.find(Instrument.class, 55);      

        Tradeticker tt = createTradeticker(message);
        tt.setInstrument(instrument);

        log.info("Persisting tradeticker: " + tt.getTradeType());               
        em.persist(tt);             
        log.info("Tradeticker persisted...");

        List<Tradeticker> last5 = em.createNamedQuery("getLast5").setParameter(1,instrument.getInstrumentId()).setMaxResults(5).getResultList();
        log.info("Persisted tradetickers size: " + last5.size());
    }

My problem is that there is no any trace of an error but still there is no any persisted objects in my Oracle database. After great number of messages call last5.size() returns 0. Log is perfectly clean.

Only restrictions for MDBs I found are I have to use REQUIRED or NOT_SUPPORTED transaction attribute on methods. My onMessage is not annotated so it uses REQUIRED as default. Also I have no any annotations on MDB class so bean should use container managed transaction.

What I'm doing wrong?

Shouldn't you manage the transaction yourself when working with a non-jta data source? That is, get a transaction and commit the data yourself? I leave that kind of stuff to JTA myself, but when I read this correctly it looks like in your case you need to commit explicitely.