Issues with messaging sample

I am having trouble getting the built-in "dashboard" sample app to work with JMS. It works fine with Flex messaging, but for some reason, it seems like it can't stay subscribed to a topic when I use JMS.

I am using WebSphere v6 with TibcoEMS v4.3 as the JMS provider.

I know I have the destinations configured correctly, because when I send a message over the chat, I can see the number of pending messages in the topic increasing. I can publish to a topic, but cannot subscribe. After turning on the EMS trace, here's what it produces when I start up the dashboard application:

[10/23/06 17:51:19:030 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: createSubscriber tsub=1871 tsess=214 topic=Topic[EMST.SS.FLEX_DASHBOARD_CHAT]
[10/23/06 17:51:19:030 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: start conn=224
[10/23/06 17:51:19:030 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: before receiveNoWait cons=1871 sess=214
[10/23/06 17:51:19:030 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: after receiveNoWait cons=1871 sess=214 msg=null

...repeats last 2 lines 6 more times

[10/23/06 17:51:19:733 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: createTopicConnection tconn=227 tconfac=TopicConnectionFactory[URL=tcp://adal54:10222;clientID=null] user=flex
[10/23/06 17:51:19:733 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: setExceptionListener conn=227 lsnr=non-null
[10/23/06 17:51:19:780 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: createTopicSession tsess=217 tconn=227 tran=false ackmode=1
[10/23/06 17:51:19:795 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: before receiveNoWait cons=1871 sess=214
[10/23/06 17:51:19:795 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: after receiveNoWait cons=1871 sess=214 msg=null
[10/23/06 17:51:19:842 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: createSubscriber tsub=1873 tsess=217 topic=Topic[EMST.SS.FLEX_DASHBOARD_FEED]
[10/23/06 17:51:19:842 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: start conn=227
[10/23/06 17:51:19:842 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: before receiveNoWait cons=1873 sess=217
[10/23/06 17:51:19:842 EDT] 00000064 SystemErr R 2006-10-23 17:51:19 [1867667001 Thread-74] [TIBCO EMS]: after receiveNoWait cons=1873 sess=217 msg=null
[10/23/06 17:51:19:889 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: close cons=1871 sess=214
[10/23/06 17:51:19:889 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: close cons=1873 sess=217
[10/23/06 17:51:19:904 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: stop conn=227
[10/23/06 17:51:19:967 EDT] 0000007d SystemErr R 2006-10-23 17:51:19 [564303409 WorkManager.DefaultWorkManager : 18] [TIBCO EMS]: stop conn=224

It looks like it's starting up, creating the subscriber connection, and then once it doesn't find something to read, Flex is closing the connection so that it can't read any new messages. Has anyone run into anything similar in the past? Any suggestions on how to troubleshoot this further?

Thanks,
Kevin