[Help] How to get this "descreen" script to show up in the Gimp menu? (Or do you have a better way to remove halftone dots?)

This Descreen script doesn't show up under "Filter" → "Script-Fu", even though I place descreen.scm in ~/.gimp-2.8/scripts/. What am I doing wrong?

The script requires the fourier plugin, which I have compiled, put in place, and tried out successfully, so that part seems to be in order.

Of course, if there is a better way of getting rid of visible halftone dots, I'd like to hear about it.

(I'm using Gimp 2.8.20 on Ubuntu 17.04.)