a question about apcupsd

I'm running NetBSD 3.0 on a Sparc Ultra1 that I want to protect
with an APC UPS.
I installed and configured apcupsd-3.8.6nb5 then made some tests.

When I unplug the serial cable I have the following message:
Serial communications with UPS lost.
When I plug it I have:
Serial communications with UPS restored.

When I unplug and plug the power cable on the APC I also have
the expected messages.

Now for the last test I put "TIMEOUT 60" in apcupsd.conf and
restart apcupsd then I unplug the APC power cable and wait
about 1 minute.
The computer initiates a system shutdown but apparently
it also shuts down the APC too early and the filesystems
are not properly unmounted.
Indeed when I restart the computer I have a long fsck.

I have some i386 machines under FreeBSD 6.1 in a similar setting
and never experienced this problem.

What did I miss?

Regards,
Thierry.