I have a customer with a Small Office Lite that doesn't light the message waiting lamps. I initially connected it via serial integration and then for some reason many years ago, that stopped working. I then manually input the on and off codes for message waiting in each mailbox and that worked fine. The system still answers, takes and stores messages but it's not sending the code to light the lamps. I rebooted it several times and noticed on start-up it does not show the "Updating message waiting lamps" screen - the field is blank. Any suggestions?