"add to devonthink pro office" command

Using this “add to DTP office” command in Apple Mail, ( I use this command a lot) i had the bad surprise to get again and again in the log window the mention “1 previously imported” (in the selected folder)- maybe I did import this mail previously but… the mail is definitely nowhere to be seen in the chosen folder, nor, I think, anywhere in the DTP dtb.
Any tip?
Thank you from

Robin, the message is probably already in your database, especially if you have already archived a mailbox.

Choose a word or phrase from a message and search (Tools > Search) for it in your database. If the message is found in your database, select it and choose Command-R (Reveal) to see where it’s stored in your database.