Great little script!
I know this topic is a bit old, but another possibility for those having trouble. Check your display settings and see how many options you have under scaled, and update the script to fit your display's options. My MacBook Pro 13" had only four options, with best as option 2, and most space as option 4 - so trying to run it without editing, the script set my display between the two, and would not change because 5 was not a valid option.
To those unsure about editing workflows: double click the Run NSAppleScript bubble, and change both 3's to whichever option is for best in your panel, and change the number 5 to the option for space.
