AMQAuthenticationException for WSO2 ESB Publisher - jms

Question

I'm trying to integrate WSO2 ESB (4.7.0) with WSO2 Message Broker (2.1.0).
This is my use case:
A generic HTTP Client sends a REST request to a PassThrough Proxy
deployed on WSO2 ESB
The ESB Proxy has an outsequence: forwards the request to the real
REST service, then, in the outsequence, it sends the response to a
mediator class (deployed inside the WSO2 ESB)
The mediator class make some stuff and has this method inside, by
which it can publish an event to a topic on the Message Broker:
Code:
private void publishEvent(){
String topicName = "MyEvent";
Properties properties = new Properties();
TopicConnection topicConnection = null;
properties.put("java.naming.factory.initial", "org.wso2.andes.jndi.PropertiesFileInitialContextFactory");
String connectionString = "amqp://admin:admin#clientID/carbon?brokerlist='tcp://localhost:5673'";
properties.put("connectionfactory.QueueConnectionFactory", connectionString);
try {
InitialContext ctx = new InitialContext(properties);
TopicConnectionFactory tcf = (TopicConnectionFactory) ctx.lookup("QueueConnectionFactory");
TopicConnection connection = tcf.createTopicConnection();
TopicSession session = connection.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);
Topic topic = session.createTopic(topicName);
TopicPublisher publisher= session.createPublisher(topic);
TextMessage textMessage =
session.createTextMessage("<asd>sono il publisher di WSO2 message Broker!</asd>");
publisher.publish(textMessage);
publisher.close();
}catch (Exception e){
e.printStackTrace();
}
}
On the other end there is a subscriber to the "MyEvent" topic which
is already running.
(I took the code both for Publisher and subscriber from this URL: http://wso2.com/library/articles/2011/12/wso2-esb-example-pubsub-soa/)
When the client sends the REST request to the proxy (1), the mediator is invoked correctly but when it tries to execute the PublishEvent method (3), nothing happens and the WSO2 ESB logs this 530 error:
INFO - ConnectionCloseMethodHandler ConnectionClose frame received
[2013-10-17 12:43:47,733] INFO - ConnectionCloseMethodHandler Error :530: not allowed:Thread-33
[2013-10-17 12:43:47,734] ERROR - AMQStateManager No Waiters for error saving as last error:Attempt to redeclare exchange: amq.topic of type topic to null.
[2013-10-17 12:43:47,735] ERROR - AMQConnection Throwable Received but no listener set: org.wso2.andes.client.AMQAuthenticationException: Attempt to redeclare exchange: amq.topic of type topic to null. [error code 530: not allowed]
ERROR - AMQStateManager No Waiters for error saving as last error:Attempt to redeclare exchange: amq.topic of type topic to null.
[2013-10-17 20:53:44,996] ERROR - AMQConnection error:
org.wso2.andes.client.AMQAuthenticationException: Attempt to redeclare exchange: amq.topic of type topic to null. [error code 530: not allowed]
at org.wso2.andes.client.handler.ConnectionCloseMethodHandler.methodReceived(ConnectionCloseMethodHandler.java:79)
at org.wso2.andes.client.handler.ClientMethodDispatcherImpl.dispatchConnectionClose(ClientMethodDispatcherImpl.java:192)
at org.wso2.andes.framing.amqp_0_91.ConnectionCloseBodyImpl.execute(ConnectionCloseBodyImpl.java:140)
at org.wso2.andes.client.state.AMQStateManager.methodReceived(AMQStateManager.java:111)
at org.wso2.andes.client.protocol.AMQProtocolHandler.methodBodyReceived(AMQProtocolHandler.java:515)
at org.wso2.andes.client.protocol.AMQProtocolSession.methodFrameReceived(AMQProtocolSession.java:456)
at org.wso2.andes.framing.AMQMethodBodyImpl.handle(AMQMethodBodyImpl.java:96)
at org.wso2.andes.client.protocol.AMQProtocolHandler$2.run(AMQProtocolHandler.java:466)
at org.wso2.andes.pool.Job.processAll(Job.java:109)
at org.wso2.andes.pool.Job.run(Job.java:157)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)
javax.jms.JMSException: Error closing connection: org.wso2.andes.client.AMQAuthenticationException: Attempt to redeclare exchange: amq.topic of type topic to null. [error code 530: not allowed]
at org.wso2.andes.client.AMQConnection.doClose(AMQConnection.java:920)
at org.wso2.andes.client.AMQConnection.close(AMQConnection.java:855)
at org.wso2.andes.client.AMQConnection.close(AMQConnection.java:846)
at org.wso2.andes.client.AMQConnection.close(AMQConnection.java:841)
at innova.esb.mediator.TopicPublisher.publishMessage(TopicPublisher.java:49)
at innova.esb.mediator.MediatorEventPublisher.mediate(MediatorEventPublisher.java:35)
at org.apache.synapse.mediators.ext.ClassMediator.mediate(ClassMediator.java:78)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:71)
at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:114)
at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:239)
at org.apache.synapse.core.axis2.SynapseCallbackReceiver.handleMessage(SynapseCallbackReceiver.java:443)
at org.apache.synapse.core.axis2.SynapseCallbackReceiver.receive(SynapseCallbackReceiver.java:166)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
at org.apache.synapse.transport.passthru.ClientWorker.run(ClientWorker.java:222)
at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)
Caused by: org.wso2.andes.client.AMQAuthenticationException: Attempt to redeclare exchange: amq.topic of type topic to null. [error code 530: not allowed]
at org.wso2.andes.client.handler.ConnectionCloseMethodHandler.methodReceived(ConnectionCloseMethodHandler.java:79)
at org.wso2.andes.client.handler.ClientMethodDispatcherImpl.dispatchConnectionClose(ClientMethodDispatcherImpl.java:192)
at org.wso2.andes.framing.amqp_0_91.ConnectionCloseBodyImpl.execute(ConnectionCloseBodyImpl.java:140)
at org.wso2.andes.client.state.AMQStateManager.methodReceived(AMQStateManager.java:111)
at org.wso2.andes.client.protocol.AMQProtocolHandler.methodBodyReceived(AMQProtocolHandler.java:515)
at org.wso2.andes.client.protocol.AMQProtocolSession.methodFrameReceived(AMQProtocolSession.java:456)
at org.wso2.andes.framing.AMQMethodBodyImpl.handle(AMQMethodBodyImpl.java:96)
at org.wso2.andes.client.protocol.AMQProtocolHandler$2.run(AMQProtocolHandler.java:466)
at org.wso2.andes.pool.Job.processAll(Job.java:109)
at org.wso2.andes.pool.Job.run(Job.java:157)
Obviously the subscriber doesn't catch any event.
What is wrong? Why do I have this Connection Exception?
Thanks a lot.