Hi there! Sorry for the delay.
It seems to me that the problem lies on the plugin command argument Subject ID, that specifies on what game character(Player, event or follower) the generator character will be applied.
Can you show to me a screenshot of the plugin command so I can see what is in there? If you are using 0, you need to make sure that the plugin command is being used by a regular event, and not a common/parallel event
I think the problem may be that the Subject you are trying to apply the generator does not exist on the map.