Can't return my book. I get an error message, E_BAD_LOAN_ID, however, I just returned a book last week and all was fine. I need to know how to fix this problem.

There is nothing really to add to this.  Everything was fine last week, I downloaded a book, read it, returned it.  This week, I downloaded a book and I can't return it.  I know it will expire on it's own, but I'd like to return it early so I can get another.  I'd like a fix for this.