Bert - given you are using a Mac, the scripts folder will probably contain both the actual script and an OSX file with the same name but a period/dot at the front. I think you selected the wrong file.
These '.' files are created by OSX but are hidden when looking at folders on the Mac. Cameras running CHDK (and Windows machines) see them however. If you have access to a Windows machine its a good idea to delete them from cards. Possible to do this on a mac but you have to make hidden files visible.
PS I wrote my own utility to show/hide hidden files in OSX , but there is a much better, free one available. It's called ShowOrHide, is really simple, works under Mac OS Sierra (and earlier). You can download it
here. The author is French, so by default the dialog appears in French (or did on my machine), but there's a menu option to switch to English.