Losing msgs on JMS Topic with durable subscriber


I am facing an unusual problem where I am losing 1 out of 5 messages being posted on a JMS Topic with durable subscription when the subscriber goes down and comes back up again :confused:

We are using webMethods 7.1.2 product suite.
I have a JMS topic defined on the wM Broker and it has 20 durable subscribers. Whenver the Integration Server hosting a subscriber is brought down and then brought up again we seem to be losing messages on the subscriber. On an average we are losing 1 out of 5 messages. Then it continues to work properly.

Every time a message is published an entry is made in the log file with the message id which can be used to uniquely identify individual messages. On the subscribing side, as soon the the trigger service receives the message another entry is made in the log file.

In the scenario defined above we can see an entry on the publishing side for the 5 messages being puiblished and only 4 entries in the subscribers side suggesting they have been picked. The missing message is not on the Broker either.

Any ideas of what I could do next?