The script looks fine...
If you do the same thing manually, on the same record, do you get a different result?
Go to your see_also field, copy the contents, enter find mode, paste the contents into your subject field and hit enter...is there anything to find?
Mock up records that you know will find something and try your script. Does it give the correct results then?
The script finally worked. I'm not sure what I did!! I really don't know what I'm doing and I think I put stuff in the calculations that don't belong there but it looks OK. Anyway, I redid it several times and finally got it to work.
Thanks for your efforts. Sorry for the trouble.