This won't work because FileMaker stored the value "$$JobKey" in the Find Request. (A quirk of how stored Find Requests work.)
In order to do this, you'll need to set it dynamically:
Enter Find Mode
Set Field [ MySQL_ODSubs::nJob_Key ; $$JobKey ]
Perform Find [ ]
Thanks MIke. That's exactly what I needed. Happy Phat Tuesday!
Alternatively you could do the following and avoid having to switch to find mode and go to a find layout:
set variable [$$JobKey, Value: "==" & MySQL_Jobs::nKey] // $$JobKey is set to ==20993
In your PerformFind use
Criterion: MySQL_ODSubs::nJob_Key from left table and enter $$JobKey on right side.
i.e. do not enter any symbols or anything other than the global variable on the right side.
This technique works for many finds where using the inserted symbols and then a variable does not work. E.g. it works for a date range, simply
set variable [$DateRange, Value: StartDate & ".." & EndDate] where StartDate and EndDate could be fields or some other variable.