[Koha] Switching from non-zebra to zebra

Hi there - I've inherited a mid-size volunteer run genealogy library server running koha 3.0. There are approx 9000 books, and people are starting to complain about non-zebra. I would like to switch over to zebra, but whenever I try to run the rebuild_zebra.pl script, I get the warning: [warn] Record didn't contain match fields in (bib1, Local-number) (and then it stops) I'm wondering if anyone else has seen this warning/error. If it is just a warning, why does it stop at that point? If it's an error, can someone give me an idea where to start looking for what it means? Thanks in advance, Amber