Installed two Leviton GFCIs yesterday, each one for that outlet only, not
protecting anything else downstream. One works just fine. The other one
doesn't: it resets OK and powers up, plug-in circuit tester shows it's wired
correctly, test button _on_the_plug-in_tester_ trips the GFCI, it resets OK,
but the test button on the GFCI itself does *not* trip it. Cycled through this
repeatedly, with no change in behavior.

Took the misbehaving one back to the retailer and exchanged it. Installed the
replacement: identical behavior.

Swapped it with the other GFCI to see if the problem would follow the unit,
or stay with the box. *Both* units work properly.

Speculations as to what's going on? I'm at a complete loss to explain this.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?