>You're right, I used a slightly different approach, but yours would have worked as well. (yeah, I'm now the expert :) ).
>
>

>Public Function Extract(fromDate As Date, toDate As Date, sp As String) As Recordset
>    Dim sql As String
>    sql = "select * from sp_aankopen('" & sqlformatDate(fromDate) & "','" & sqlformatDate(toDate) & "')"
>    Debug.Print sql
>    Set rs = New ADODB.Recordset
>    rs.Open sql, conn, adOpenDynamic, adLockOptimistic, -1
>    Set Extract = rs
>    Set rs = Nothing
>End Function
>

>
>I see now what I did wrong. :)
>
>Many thanks!

Embedding parameters into a sql string is not a good approach. Parameters need to be send as parameters, not part of a string.