User defined Locator/extension script not running


I tried to get “sample-locator-builder.js” extension running, but I think without success. I added it under “extension Scripts” to Katalon Recorder.
I modified the script just to be sure that the extension is working like:
return “css=” + e.tagName + ‘#’ + +‘#ImRunning’;
I know, this wont work during playback, but it should be recorded this way. When I have a look at the target combo box in the recorder after recording a script, I expected to see this dummy locator among the others, but it’s not shown.

Thank you very much