I have a feeling I might know what the problem is (not 100%) In 1.0.x the callbackservers are keyed only on the consumer id, which is created on the server from a sequence that starts from zero on startup. So, if you have more than one server you can have more than one consumer with the same id, which can cause problems. I fixed this some time ago in TRUNK and now the server id + the consumer id used as the key, although this fix is not available currently in 1.0.x View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3984591#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...