DELETE DUPLICATE EMAILS

AllardBeerthuizen Thank you for pointing me to the Delete Duplicate Emails script. I must be doing something wrong. I downloaded the file "Remove-DuplicateItems.ps1" and double-clicked on it. It's a text file that describes the script. I went to (external link removed by moderator) and read Michel de Rooij's article. In a Cmd window I ran "Remove-DuplicateItems.ps1 -Identity Patricia -Type Mail -Retain oldest -DeleteMode MoveToDeletedItems" in the directory that "Remove-DuplicateItems.ps1" is located, copying the format of the script Michel ran in his example. Nothing happened. No error, no messages of any kind, no files in my Deleted folder, and duplicates are still in my Inbox. What am I doing wrong? 

Patricia