Modules & VBA :: Cannot Set Outlook Send Using Account

A client wants to e-mail newsletters using a non-default Outlook account. The code below does everything the client needs except setting the SendUsingAccount. In debug I can see that the correct account is assigned, yet all of my testing results in e-mails where the From line is the default account. The test setup uses my own isolated SMTP server, so when I look at the e-mails sent the sender is the default account. The default account's Sent folder shows the sent mail, which is not what we want.

Code:
Sub prepEmail()
Dim frm As Form, startDate As Date, endDate As Date
Dim rs As DAO.Recordset, strSQL As String, intNewsLetter As Integer
Dim rsEmail As DAO.Recordset, rsNewsletters As DAO.Recordset
Dim OlApp As Object, ol As Object
Dim olMail As Object, olAcct, olAcctTemp

[code]...