Quote - OK that squashes that idea :)

Are the lights in a remote runtime library?
If so does it work if they are in the local library?

I've tried both -- selecting lights from the local library and remote runtimes. I get the same phenomenon.

Once I do select a light set manually (from the "Please locate file..." dialog), Poser remembers that directory, and looks for any selected light sets there. If I subsequently choose a light set from that directory, the script finds it. But if I browse to another directory and choose a light set, Poser asks me to locate the file again when it tries to load it.

Interestingly, the script also seems to remember the LAST directory from which I manually selected a light set, even between restarts of Poser. I am not sure how that's happening, since I added no code to store that information.