Thanks Ducks! I guess you're right... The way I got them on the internet is with Author, Title, etc. all in the name of the file. (mostly pdfs). If I straighten that out by editing the metadata and putting things where they go, then Calibre is able to locate, download, and apply the additional metadata.
It seems strange that so many worked in previous weeks, then none... But I guess it was just a coincidence. This leads to another question about how a person might parse "metadata-like" info upon importing into Calibre. I guess I'll start another thread for that though. Thanks again. -steve
EDIT: Won't need that other thread... There's a whole regex system for adding books.