"printer power switch" does not work

[river folio]

I have followed these instructions: https://docs.mainsail.xyz/overview/quicktips/printer-power-switch

Image of error posted

My config:

[power printer]
type: tplink_smartplug 
address: 192.168.221.250
restart_klipper_when_powered: true
bound_services: klipper

I've also tried changing "true" to "True" in that - no change

Solved.