when you marked each instance of a particular case, did
you use the short form to mark it?  for example, if your
first case is smith v. jones, the short form would be
smith, and each instance of smith would be marked as
smith.  if you did that, it should work.  in options, do
you have passim unchecked?  when you run the table, make
sure you go to the top of the menu that appears on the
right, and select all (otherwise you will only update,
say treatises, without updating the entire table).
usually this problem comes from not using short forms.

See http://addbalance.com/usersguide/complex_document.htm for more info on
building a Table of Authorities.