Change your code like this:
Code:
Newdir = "C:\adjudex\documents\"
Filename = Directory & Dir("C:\adjudex\documents\temp", vbNormal)
Newname = Dossier & "Dossier_privé_Confirmation.pdf"
NewFile = Newdir & Newname
Name Filename As NewFile
By the way, I would use strFileName and strNewName and strNewFile instead just so you ensure you do not accidentally use any Access Reserved Words as variable names.
Oh, I just realized that you also don't have the proper name for the original file. You are asking it to rename the DIRECTORY instead. This:
Filename = Directory & Dir("C:\adjudex\documents\temp", vbNormal)
Is not correct. You would need the file extension too
Filename = Directory & Dir("C:\adjudex\documents\temp.pdf", vbNormal)