I posted a WL book & it was requested.  Before I could mail it out, I received a pm asking me to cancel the order, which I did.  The book isn't on my bookshelf or on hold for somebody else's WL (it has 7 people wishing) response.  Do I need to repost it?  I've never had this happen, and I'm not sure what to do.  Thank you for your help.

Yes.  When you cancel, the site assumes that means you've found you can't ship the book because you've found it is damaged or you can't find it, so it is automatically removed from your shelf and you have to repost it (and you lose your place in line if there are other copies).

Usually the requestor should be the one to cancel, but they can't once you've printed the label. 

As this is a wishlisted book though, simple enough to just repost it.

Cheers, -bret

Since you cancelled, you need to repost it.  Hopefully the person that asked you to cancel took the book off their WL, otherwise the book will go right back to them.

Okay.  Thank you guys very much!

If it does go back to the same person, don't cancel it, let them do it.  That way it will move on to the next person in the list.