Yes this should work. Are you using Get ( DocumentsPath ) to compute the documents path and set that text to a variable?
Set Variable [$Path ; Get ( DocumentsPath ) & "FileNameHere.fmp12" ]
I tried it both these ways:
Set Variable [$Path ; Get ( DocumentsPath ) & "Subfolder1/Subfolder2/FileName" ]
Set Variable [$Path ; "filemac:" & Get ( DocumentsPath ) & "Subfolder1/Subfolder2/FileName" ]
Neither worked. Perhaps it fails because it's two level deep inside the Documents folder. I'll experiment with this tomorrow. I may have to resort to scripting Troi File moving the file to that folder.
The basic syntax that your are using is correct. becareful both to correctly specify the file extension and make sure that your sub folders actually exist inside the documents folder and are correctly named in your file path.
You can also see this thread: Exploring the use of a $Path Variable in Scripts
To get a file that you can use to check file paths. You can open this file and use insert file with the "by reference" option enabled to insert a file from your intended destination into a container field. Then check the calculation fields that return a file path extracted from the container field. You can compare the resulting file path to what you are using in your script.
Silly mistake on my part. I had forgotten to change the target of the Save Copy As script step to just a variable. It had previously been a mixture of a file string plus variable, and I had switched to using just a variable and forgot to update that one line. It's all working fine now.