Problem with Oracle AQ ESB-aware Queue

[mike_ap]

When I setup an Oracle AQ queue with a gateway listener (is-gateway="true"), I have no problems. But when I setup an Oracle AQ queue with an ESB-aware listener (is-gateway="false") I start getting the following messages:

10:45:47,935 WARN [MessageAwareListener] Error processing courier, backing off for 1000 milliseconds
10:45:48,935 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:45:49,935 WARN [MessageAwareListener] Error processing courier, backing off for 2000 milliseconds
10:45:51,950 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:45:52,950 WARN [MessageAwareListener] Error processing courier, backing off for 4000 milliseconds
10:45:56,950 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:45:57,950 WARN [MessageAwareListener] Error processing courier, backing off for 8000 milliseconds
10:46:05,966 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:46:06,966 WARN [MessageAwareListener] Error processing courier, backing off for 16000 milliseconds
10:46:22,966 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:46:23,966 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:46:56,106 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:46:57,106 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:47:29,121 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:47:30,121 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:48:02,137 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:48:03,137 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:48:35,137 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:48:36,137 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:49:08,152 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:49:09,152 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:49:41,152 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:49:42,152 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:50:14,167 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:50:15,167 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds
10:50:47,167 INFO [JmsConnectionPool] Received NamingException, refreshing context.
10:50:48,167 WARN [MessageAwareListener] Error processing courier, backing off for 32000 milliseconds

Any ideas on what the problem might be?