Good morning,
This is a bit weird!
I have checked the IIS log and it shows
2019-07-15 06:54:48 W3SVC87 92.53.241.24 GET /MyFolder/MyPage.aspx =AmIARobot=No
Note the lack of ? and a space before =AmIARobot=No
I was using this param as way of stopping any search engine that found the page causing the page to do what it was supposed to do.
I copied and pasted the url from the Scheduled Tasks screen directly into a browser and it does have a ? and it does what I wanted.
So I have removed the check for the parameter and the page works correctly as a Scheduled Task.
It appears that the scheduled task to doing some kind of processing of the url which makes the use of a parameter impossible.
Bye
Ian