cannot find UPS device?

I'm getting this error message:

Nov 24 19:37:53 Tower apcupsd[1735]: apcupsd FATAL ERROR in linux-usb.c at line 609 Cannot find UPS device -- For a link to detailed USB trouble shooting information, please see .
Nov 24 19:37:53 Tower apcupsd[1735]: apcupsd error shutdown completed

I checked the cables but they're plugged in. I restarted the server, with the same error. Does this mean the UPS is bad?

Update: tried a new APC UPS, with a new USB cable, still getting the error message.

Update2: problem was probably due to two different versions of apcupsd co-existing and conflicting as implied by some error message. Upgrading to a newer Unraid version and downloading the apcupsd to a fresh installation seems to work.