Data type mismatch in criteria expression.. sql = "select Value from

Dim oConn As ADODB.Connection
Dim adoRS As ADODB.Recordset
Set oConn = New ADODB.Connection
Set adoRS = New ADODB.Recordset

oConn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\test\;Extended Properties=dBASE 

IV;User ID=ADMIN;Password="
 
 sql = "select Value from " & "090615AF.DBF" & "  where  Date = '20090615' " 
 adoRS.Open sql, oConn

 Do Until adoRS.EOF

 adoRS.MoveNext
 Loop
 adoRS.Close
 oConn.Close