I believe if you are going to use a SELECT statement with a recordset object you want to instead do:

set rst1 = CreateObject("ADODB.Recordset")

and then

rst1.Open "SELECT DISTINCT cname FROM agencycodes", oConn

If you ar usn an Execute method then you don't even need the recordset object. However, because you are using a SELECT query you will want to use a recordset.