Alexa Fire TV with Echo Dot on / off?

EchoDot and FireTV are paired. Every Alexa command for the FireTV (from games lucifer to open Netflix etc.) works. But with the commands "Alexa, start FireTV Stick" and "switch off FireTV Stick" it doesn't work.

Is that actually possible?

Does not work because the on / off function is separate from the rest. It is at the same address as on a DVD player, so it can only be activated by remote control (stick or TV).