I'll just go ahead and answer this, since I found someone who fixed it -- in case it helps someone. First off, it should be noted that the ab, cd, etc. are placeholders and not actual strings. Second, for some strange reason the "general" format sometimes makes it difficult to operate on logical expressions. Who knows why, but the OR() vars needed no quotes, and the others did...go figure.

I've definitely become a Mac user over the last few years, but this is one area where #%*! Apple. So much of Excel's developer stuff is missing or not as good. Hope this helps another iPerson.