Randomize Function Problem

I'm using a randomize function to display a different featured product, but there are certain items that I want to omit. Here's the code I'm using:

<%
Set conn = Server.CreateObject("ADODB.Connection")
conn.Open "Driver={Microsoft Access Driver (*.mdb)}; DBQ=" & Server.MapPath("/theDB.mdb")
randomize
rdm=int(rnd*15)+246

sql = "SELECT * FROM kbs WHERE kbs.id = " & rdm & " AND kbs.subject NOT IN (20,21)"
set rs=conn.execute(sql)
%>

It's selecting a range of product IDs and it's s'posed to exclude all IDs whose subject is either subjectID 20 or 21. It works fine except when it comes to items with those subjects and then it displays this error message:

Either BOF or EOF is True, or the current record has been deleted. Requested operation requires a current record.