Electrical – Troubleshooting: Why does the multimeter not work when a non-contact volt detector shows current

I recently purchased a 1970's home, and the lights in one room don't work. Troubleshooting yields odd results, and I don't know where to check next.

The room

A fairly standard secondary room on the second floor.

• One switch to a standard ceiling light fixture – non-working.
• One switch to a closet light fixture – non-working.
• Outlets around the walls, all of which work just fine.

The room is controlled by a single breaker, which works as expected, cutting all power to the room.

The non-contact tester

Using a Fluke, non-contact tester – the "VoltAlert" made to be stuck into an outlet – I don't get any results (as expected) when placed on the plate of any wall switch in my house, whether the switch is off or on. The only exception is the switch for the light in question, which lights up when the tester is 4-5 inches from the switch. I have no idea what could be causing such a result. It's just as sensitive around the light fixture – making it impossible to test an individual socket.

Flipping the breaker does cause all tests be negative, so at least we know the line from the breaker box to the switch is working.

The switch

The switch appears to be fairly new (blue plastic back), and is wired on the hot side. The rest of the wiring in that box appears to be done correctly. The hot line comes in near the baseboard and into the bottom of the box, and the switched line exits the top and continues up toward the ceiling.

The multimeter

This part throws me. I can't get my (cheap) analog multimeter to return any reading. I've tested both incoming and outgoing hot wires against the ground, both with the switch on and off, and I get no result. I tested a nearby outlet just to make sure it wasn't the multimeter, and got normal results.

The light fixture

It's old and is what I initially assumed to be the problem. Bulbs that are known to be good do not work. When the switch is off, the fixture still reads hot on the non-contact testers, despite the fact that this is a terminal. The multimeter also does not give any result when testing the hot/neutral behind the lighting fixture while the switch is on. This leads me to believe that the problem would persist beyond changing the fixture.

Ultimately, I've eliminated enough issues that I don't know what to test for next. I'm hoping someone with more experience has seen something like this before and can advise on the next most likely cause. Thanks in advance for any advise.