Enabling Motion Detection via API

I’m trying to toggle camera motion detection mode via the web API using http://xx.xx.xx.xx:8124/Json/StartStopMotionDetector?source=3&enabled=true&authtoken=xxxx

however, this just returns false. How can I toggle the mode using API?

The command is wrong. Should look like this
It seems to be source that should be sourceid


http://xx.x.x.x:8124/Json/StartStopMotionDetector?sourceid=2&enabled=true&authtoken=89d35ec4-c2f8-4bf3-8e01-xxxxx still returns false.

Is the return value the actual motion state or the result of the enabling method?

I used it yesterday, so
-Case sensitive?
-Used the correct token?
The return is result of the enabling method.