Do you have the raw data for your tables?
I'm not sure exactly what is wrong, but
-I don't see your autonumbers when I look at your data in datasheet view??
-your query doesn't sort correctly
-you have 3 records in author table with no (NULL) author
My best guess is it stems from your use of Lookup at table field level.
You have authors and books
An Author can write 1 or more books
A book may have 1 or more authors
In my view the proper relationships would be as follows:
Author--->AuthorOfBook<--- Book
Code:
AuthorID -----> AuthorID,BookID<----BookID
AuthorName BookTitle