Invalid sequence number was passed in

Hi

We are getting continuously this error on IS.Please throw some light on this issue.

while executing trigger. Rejecting Document for TriggerStore:CommonUtil.errorHandling.triggers:subscribeErrorDocument.

2014-07-28 00:43:20 PDT [ISS.0098.0049C] Exception:com.wm.app.b2b.server.dispatcher.exceptions.TransportException: Invalid Sequence Number (277-1773): Invalid sequence number was passed in.

while executing trigger. Unable to ack Document for TriggerStore:CommonUtil.alertNotifications.triggers:subscribeAlertDocument.

2014-07-28 00:43:31 PDT [ISS.0098.0049C] Exception:com.wm.app.b2b.server.dispatcher.exceptions.TransportException: Invalid Sequence Number (277-1773): Invalid sequence number was passed in.

Thanks in Advance