ADO returns different results from Union Query

[Tod]

I have a Union Query in Access that combines from data
four other queries. It works just fine. It returns exactly
the correct results. However, if I use ADO from another
program (Excel in this case), like this:

cn.Open "Driver={Microsoft Access Driver (*.mdb)};Dbq=" &
ThisWorkbook.Path & "\DatabaseName.mdb;"

sql = "Select * FROM UnionQuery"

rs.Open sql, cn

The recordset only contains results from three of the
queries. Is there something about Union Queries that would
make Access return one set of data and running that same
query using ADO would return a different set?

tod