Why is it that if I do a search and find a book, I can see the list of Subjects like this:

Children's Books >> Arts & Music >> Music >> Songbooks

But if I do an Advanced Search, I can only expand it to this level?

Children's Books >> Arts & Music

I like the Subjects better, because I can narrow it more for the topic,  but I like the Advanced Search to be able to limit a search by, for example, publication date.  It seems like it would be very easy to have the Advanced Search expand the same way the Subject one does. Is there a reason why it won't expand the same way?