Keep looking Bob, they will be in there, a small plastic bag of countersunk a4 rivets can be hard to find, they are usually in the same box as the big bag of a4 domed. There should also be a smaller bag of a5, also small bags of a3, a bag of a5 countersunk, a bag of a5 longer rivets, a bag of large head black painted rivets, and a bag of a5 stainless steel, so if you find any of those the the countersunk ones you're after will be there too.