We are usin V3.5. The problem is that we have merge fields with "_" in their names (ex: MyMergeField_1)
When we call MailMergeWithRegions, it truncates the field name just before the "_" (MyMergeField_1 ==> MyMergeField) so it's looking for a field with a shorter name. If no field with the short name exists in the document, no merge is done...
We have a lot of fields with "_" in their names. This bug was not present with the previous version we used (Aspose.Word 3.3.3).
Thank you for prividing us a solution.