Book are not sold out by using join

Question

which book are not sold out in Book table and given Book name

Book
BID	Bookname	pricecode
1	Harry potter	AB01
2	Sheldon	AB01
3	Dan brown	AB01
4	Cindrella	AB01

 

Sold
ID	BID	sold date
1	1	9/13/2017
2	2	9/12/2017
3	4	9/15/2017
4	8	9/19/2017

 

select Bookname from Book Join sold  on Book.BID=Sold.BID where sold date IS null 

--i am not getting expected output