On 11 Jan 2007 19:21:49 -0800, wrote:

Sorry -- my bad explanation.

Yes, I've tried all the blacks together -- and all the whites -- and I

That is the only way you should connect it. The results of other ways
are "unpredictable". But may melt some wires before the breaker
has a chance to trip.

still only get (1) bulb. There is a single switch that controls the
fixture. But the line continues upstairs to (3) other lights (all
controlled by their own switches) -- and there is at least one outlet
on the same run.

None of this matters. Nor does the age of the house or its condition.
If one bulb lights you have electricity between those two wires that
come out of the ceiling. If one socket doesn't light and you know the
bulb is good (You tested the bulb before putting it in that socket,
but to be certain you should test it after also.) then it is the
socket.

Although it is very unusual for a new socket not to work, it is not
like flipping a coin where getting heads the first time has no effect
on the second time. If they made one bad socket, it's not so unlikely
that they use a defective system for making sockets, so it's not so
surprising that the next one doesn't work. Even though the factory is
far away, the assmbly line puts them in cartons in sequence as they
are made, and your two fixtures probably came out of the same carton.

I switched the bulbs (put the working one in the non-working socket) --
and, I even returned the fixture (thinking the socket was faulty).

New replacement fixture = same result.

Can't figure it out...