I use a dummy filename "c:\11.pdf" for all my scanned pdf files. I then moved the this 11.pdf file to its appropriate folder, and rename it to something very similar to a selected file. My logical steps are;
Navigate to that appropriate folder
Select a file
Move c:\11.pdf to current lister
Rename c:\11.pdf to the name of current selected file, adding "_new" to the end.
You shouldn't need quotes around the C:\11.pdf as there are no spaces in the name. The new filename would need quotes if it contains spaces and you could add quotes around "{o|noext}_new.pdf" if you wanted although Opus should add them in automatically.
If you change the command to this:
echo Copy C:\11.pdf MOVE HERE AS {o|noext}_new.pdf
pause
and change the type to MS-DOS Batch function it will print out the command that is being run which might give a clue as to why it's failing.