This is not going to help for switching off - WOL = Wake On Lan, it never turns anything off.
The message tells you what it was looking for, have you tried that? You have to put the whitelist file in the right place as well.
Because the exec Thing run channel tells you what the binding is doing, as it explains in the docs. When the script starts to run, the channel turns on. When the script exits (probably just a few milliseconds later), the channel turns off.
You will not be able to use this channel to represent the on/off state of some remote PC
Have you looked at this thread?