@Engineer_Dan 

From the wiring description of the dumb switch, that is a 3way switch.

You need to use the HS210 to replace it.

B.Will wrote

@Engineer_Dan 

 

From the wiring description of the dumb switch, that is a 3way switch.

You need to use the HS210 to replace it.

 

@B.Will 

Thanks for the response, but no, that is the only switch controlling that light.

@Engineer_Dan 

I'm with @B.Will on this. If it was a stand alone switch you would normally have two black wires and the neutral wire. In your case the red wire it typically seen in 3-way switches.

Here is a FAQ that breaks down identifying a 3-way switch: https://www.tp-link.com/us/support/faq/2009/

@Engineer_Dan 

Did you ever get a solution to your problem... I am having the same issue. WIred correctly, but no light. Doesnt make any sense.

@atomicow same problem here. Can't make sense of it. It powers on but the light won't come on

@Engineer_Dan I have 3 HS200 switches installed by an electrician about a year ago to control exterior light fixtures. Two of them have worked perfectly. The third started acting up and I had to play with the remote app to get the light to go on. Then it worked fine for a few months. Now nothing I do will turn the light on. I have tried other bulbs, so that's not the issue. How can I tell if it's the fixture or the KASA without calling the electrician?

@guacdaddy 

If the app shows that the device is on/off when you tap on the device in the app, and the app shows on/off when you press on the switch, then it more then likely is the wiring/fixture.

@Engineer_Dan 
@atomicow 

I have the same problem. HS200 can connect with app. and press the HS200 device or app to turn on/off it.
but the lamp no response. always turn off..
Have you fixed this problem?

@Engineer_Dan 

It appears your existing wall switch is a 3 way switch. Does that light turn off from another location? If it does you may need HS 210,  3 way switch 2pk (you only need to use one HS 210 switches). 

Engineer_Dan wrote

I'm baffled.  I want to install a Kasa HS200 in place of a mechanical switch to operate a ceiling light.  The existing installation has 4 wires - black, red, white and bare copper ground.  The machanical switch wires were connected as follows (looking at the wall):  Black wire to top right connector on switch, white wire to bottom right connector, red wire to top left connector.

 

On the Kasa, I tied the white wire to the existing white wire, the existing black wire to one of the black wires on the Kasa, the existing red wire to the other black wire on the Kasa, and the green wire on the Kasa to the existing bare copper ground wire.

 

I connected the Kasa to my network with no problem.  I can use my phone or press the Kasa to operate the Kasa, and I hear a click from the Kasa and see the indicator on the Kasa switch states.  All good.  However, the light the Kasa is connected to doesn't come on.  I pulled the Kasa and put the mechanical switch back in and the light works as it should.  Reinstalled the Kasa (checking carefully to make sure the connections were solid) but the light still doesn't turn on.

 

Any suggestions on something to try?

I've got the same problem. 2-position older switch. Connected to network. LED goes on and off. Clicks. Zero power. Light works with regular switch.

Kind of a joke if you ask me.@Engineer_Dan