UPS monitoring "out of spec"

I have two ReadyNAS NV+ version 1 systems. One is connected to an APC UPS and is showing that it is OK. It is also configured to accept connections from other ReadyNAS systems for UPS monitoring. The second system is configured to refer to the first for UPS status. When this is done, the second system says that it has connected OK, and this is recorded in the log. The correct UPS status is shown in text and the indicator is green. The second system can ping the first in less than a millisecond. But after a minute or two, the second system reports:
UPS 1 Remote Error, Battery charge: 0%, 0 minutes Out of Spec
There is nothing new in the log, since the message "Successfully connected to remote UPS server". The first system is still showing UPS details and OK. Both systems are running RAIDiator 4.1.10 [1.00a043]