I ordered some books from person in a deal.  Person is unable to locate some of the books one being one of the ordered books.  Person said to let them cancel.  I think I should cancel so it doesn't roll over.  So who should cancel???

Thanks for help.

You should cancel. You don't want her or the system to do it because the requests will go to the FIFO system to people not offering the deal. The only time you want to sender to cancel is if it is a Wish List book.

Usually, the rule of thumb is that the person who isn't waiting in line (wish list line, or the line to mail a book) cancels. 

But in this case, since you do not want the books if they aren't part of a deal, Melanie hit the nail on the head.  You need to cancel.