Script not available during uninstall

Hi there.

I have a script that I use during install. It's included like so:

bit = require('numberlua');

It's included as a Primer file and "use during uninstall" is ON.

This works fine during install, but during uninstall I get an error saying it can't find 'numberlua' with a list of paths it tried.
I've looked through the UI and cannot find anywhere that solves this issue. What else do I need to do to make script files available during uninstall?

Thanks
Aaron