Your mailmerge field coding appears to be based on the MS articles rather than the tutorial you downloaded. The coding in the MS articles won't do what you want; you need the tutorial's field coding for that. For some worked examples, see the attachments to the posts at:
https://www.msofficeforums.com/mail-...html#post23345
https://www.msofficeforums.com/mail-...html#post30327

Another option, if your workbook has a separate sheet with just a single instance of each of the grouping criteria, would be to use a DATABASE field in a normal ‘letter’ mailmerge main document could be used without the need for a macro. For an example of that, see:
https://answers.microsoft.com/en-us/...f-8642e46fa103
The DATABASE field can even be used without recourse to a mailmerge, though that may not suit your requirements. An example of such usage can be found at: https://www.msofficeforums.com/mail-...html#post67097



Alternatively, you may want to try one of the Many-to-One Mail Merge add-ins, from:
Graham Mayor at http://www.gmayor.com/ManyToOne.htm; or
Doug Robbins at http://bit.ly/1hduSCB

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]