hibernate3.5 jta事务问题

第一次使用jta事务，使用的服务器为jboss5。代码如下 ：
hibernate1.cfg.xml

	<session-factory>
		<property name="connection.driver_class">
			com.mysql.jdbc.Driver
		</property>
		<property name="connection.url">
			jdbc:mysql://127.0.0.1:3306/hibernate1
		</property>
		<property name="connection.username">root</property>
		<property name="connection.password"></property>
		<property name="dialect">
			org.hibernate.dialect.MySQLDialect
		</property>

		<property name="transaction.factory_class">
			org.hibernate.transaction.JTATransactionFactory
    	        </property>
		<property name="jta.UserTransaction">java:comp/UserTransaction</property>
	        <property name="hibernate.transaction.manager_lookup_class">
                              org.hibernate.transaction.JBossTransactionManagerLookup
                 </property>

	         <property name="show_sql">true</property>
	
		<mapping resource="com/hibernate/domain/Person.hbm.xml" />
	 </session-factory>

hibernate2.cfg.xml

	<session-factory>
		<property name="connection.driver_class">
			com.mysql.jdbc.Driver
		</property>
		<property name="connection.url">
			jdbc:mysql://127.0.0.1:3306/hibernate2
		</property>
		<property name="connection.username">root</property>
		<property name="connection.password"></property>
		<property name="dialect">
			org.hibernate.dialect.MySQLDialect
		</property>

		<property name="transaction.factory_class">
			org.hibernate.transaction.JTATransactionFactory
    	         </property>
		<property name="jta.UserTransaction">java:comp/UserTransaction</property>
	        <property name="hibernate.transaction.manager_lookup_class">
                      org.hibernate.transaction.JBossTransactionManagerLookup
                 </property>

	         <property name="show_sql">true</property>
	
		<mapping resource="com/hibernate/domain/User.hbm.xml" />
	</session-factory>

测试代码:
       

              UserTransaction ut = null;
		SessionFactory sf1 = new Configuration().configure(
				"hibernate_db1.cfg.xml").buildSessionFactory();
		SessionFactory sf2 = new Configuration().configure(
				"hibernate_db2.cfg.xml").buildSessionFactory();
		try {
			Context context = new InitialContext();
			ut = (UserTransaction) context.lookup("java:comp/UserTransaction");
		} catch (NamingException e) {
			e.printStackTrace();
		}
		try {
			ut.begin();
			Session s1 = sf1.openSession();
			s1.save(p);
			s1.close();
			Session s2 = sf2.openSession();
			s2.save(u);
			// 查询
			User user = (User) s2.get(User.class, 44);
			System.out.println("name=" + user.getName());
			s2.close();
			ut.commit();
		} catch (Exception e) {
			e.printStackTrace();
		}

          

执行结果：

10:37:30,250 INFO  [STDOUT] Hibernate: select user0_.id as id2_0_, user0_.name as name2_0_ from user user0_ where user0_.id=?
10:37:30,328 INFO  [STDOUT] name=小明

没有insert语句，数据库也没有结果。
那位同学帮忙看下原因。

BTW:表是innodb的