We are using Arcserve on a Win 2003 Server Box for our nightly backups. Our Backup Job has NOT changed in two years. With the exception of New tapes every few months NOTHING has changed. Now for some reason when I add a new out of the box or formatted/erased taps it does the back up job fine BUT it gives NO serial number. The serial number box is BLANK! No errors it backs up fine and I can use this back up tape with no SN when it asks for the tape with No SN and it works ok. My problem is now that we are replacing old tapes with new tapes and storing our weekly's & monthly's the new taps aren't assigned ANY serial numbers. I've even created a few test jobs and they are not assigned serial numbers either. Please Help 500 points to the first person who can solve this puzzle?