Voice command of your "... with Netatmo" by Amazon Alexa connected light switches and power outlets requires the use of the right words.
Below you'll find a non-exhaustive list:
Power outlets and lights
"Alexa, turn on the coffee machine"
"Alexa, turn off the camera"
"Alexa, set the light brightness to 30%"
"Alexa, turn on the kitchen"
"Alexa, turn off the kitchen"
"Alexa, activate Away"
"Alexa, activate Sleep"
For further information, we recommend you visit the Amazon site.