@Hillary5 , what dates are you talking about? I, or anybody else here, could double check for you and see/tell you if those dates are really blocked out now.
A pre-approval expires after 24 hours. when did you send it? sometimes it says "not possible" if those potential guests have now booked somewhere else for those dates. It doesn't help that Airbnb constantly changes their wording on this. I had this pre-approval situation last week, and 20 min. after I had sent out the pre-approval, it says in my message folder, "soandso won't need it any longer", meaning to me that they booked elsewhere. Possibly there is also a different wording for US bookings vs. UK bookings....
In any case, if it is a confirmed booking, you should have reveived an email from Airbnb, with itinirary and confirmation number. did you get that?