How to prevent empty book entries (no linked files) in my library

[elligator]

Hi,

I'm a new calibre user. Sorry if this has been asked before, but I searched and didn't find the answer to my question.

When I import books into my libraries (I have a few different ones) at least 1/3 of the "books" are not linked to the actual files. They have metadata and covers, just no linked filetypes. I then have to go in and manually find the files for each one, before I can send them to my device. Am I importing them the wrong way, or is there some other fix for this? I have been using the "add books from directories, including subdirectories" choice.

Thanks!