Why would someone post a wishlisted book and then cancel the request for it?  This has happened to me twice in the last week for the same book???!!!  This last one the reason was she/he was cancelling her/his membership!!!!

I know it's disappointing!  

There seems to be several reasons:

mistake posting.

They cannot find the book.

They discovered the book is Unpostable.

They posted and it went thru several wishers without being accepted and now they cannot mail. 

Life happened and they cannot mail.  

I had to cancel a request this week.  Granted, it was not a WL book, but it wasn't due to my wanting to cancel.  Due to an ice storm I've had no electricity at my house for over 4 days now & will likely not have it back for at least another week since so many power lines are down.

So sometimes things happen. It can be frustrating, but hopefully you will get the book soon!

Once my electricity is back up & running I will put my account back up which I think will post the canceled book to the person requesting it since the requester is the only wisher for it so I will still (hopefully) get to post the book to her & she will still get it.... unless someone else posts it to her before I can do it, of course.

And hopefully you will get your book soon.

The person may have posted books and then realized the club is not something they wanted to do. A lot of people don't read what they are getting into before jumping in. Its very disappointing for the wisher, but at least they cancelled the request and got you back into the WL and didn't mark the book mailed and then never bother to do it.

If your wish list was not on auto it may help to put your wish list on auto.. 

A lot of people don't read what they are getting into before jumping in.

I think there's definitely a number of people who join and post books that they're not sure they want to trade.  They don't know they have to mail the books if requested.  Also they don't know about wl books and they get overwhelmed with immediate requests. 

I did this week.   My area ended up flooded and I could not get to the post office.  I didn't expect it to be that bad as ghe promised our new levies would hold.  Ha!  Now that the water is receding I am back to posting.  Sometimes things happen oyt of our control.

Sometimes it's things out of someone's control, but it happens enough that I'm willing to bet that sometimes it comes down to someone just not wanting to send it ..

Is it really that often? I get a fair amount of WL books posted to me and I can't remember the last time one was cancelled.

Yeah, I had one cancelled in DEC (twice by the same poster) and they never gave a reason.  Perhaps they were 'cancelling' instead of marking that it didn't meet my RC (no smoking one is all I have).