Dynamic Subject Line Email Merge

[MHutcheson]

I have a Word 2010 document linked to an Access 2010 data source. When a
user clicks a button in Access, the Word document loads and performs a
email merge using the below VBA code:

Private Sub Document_Open()
With ActiveDocument.MailMerge
Destination = wdSendToEmail
SuppressBlankLines = True
MailSubject = "Your Refund " &
ActiveDocument.MailMerge.DataSource.DataFields("Return_code").Value
With .DataSource
FirstRecord = wdDefaultFirstRecord
LastRecord = wdDefaultLastRecord

End With
Execute Pause:=False
End With
End Sub

However, as the .mailsubject part is not in the loop it is only
retrieving the first Return Code. I have tried to integrate in the loop
to no avail using this code:

Dim i As Integer
Private Sub Document_Open()
With ActiveDocument.MailMerge
Destination = wdSendToEmail
SuppressBlankLines = True
With .DataSource
FirstRecord = wdDefaultFirstRecord
LastRecord = wdDefaultLastRecord

i = .DataSource.DataFields.Count

Do While i > 0
MailSubject = "Your Refund " &
ActiveDocument.MailMerge.DataSource.DataFields("Return_code").Value
i = i - 1
Loop

End With
End With
End Sub

But keep receiving the message the data member (.DataSource) is not
found.

Where am going wrong?

Regards,

Michael