@Alexandre-Sousa, does your command run but Alexa says nothing? Also, which Alexa skill are you using? If you're saying, "Alexa, turn on X", that's the Smart Home skill, which doesn't use the Voice Reply field.

@Rafael-Karczevski, yes. The Smart Home version of the skill simulates a Smart Home switch that you can turn on or off. So Alexa or Google Assistant's audible response is just to confirm the "switch" was flipped.