@TimGre 

What is the error message?

Once Alexa is linked up with Kasa, tell Alexa to discover devices. It will say if it discovered devices. When you then open Alexa, on the top right scroll to the right and select all devices, you shoudl see the plugs listed there.

From there, you hit the "+" on the top right and add the group then selecting the devices you want.

@Tony for example - the devices are called lamp 1 and lamp 2. They work fine. I created a group - have given it a variety of names - for example house. In the Kasa app I can turn on or off both via the group house. But if I say "Alexa turn off house" it says "do you mean lamp 1". Using discover in the Alexa app shows both lamps but not the group 

@TimGre 

Try to tell Alexa, "Turn off house lights".

I think Google Home is similar in referring to the group as lights.

@Tony same result. I also tried the Good night scene with no success 

Tim

Fixed it. I was creating the group in the Kasa app. When I created it in the Amazon Alexa app then it worked