What I am trying to do is to write a query that finds all records in Table ADS that do not have a corrisponding record in the tables PROOFS. Help

SELECT *
FROM Ads
WHERE AdNums NOT IN
(SELECT Proofs.AdNums
FROM proofs))

Ads
AD_ID Long
RevisionDate Date
AdNums long

Proofs
Ad_ID
.....
AdNums long


Ads