SetAttr Meta copyfrom

I am trying to construct a couple of scripts to allow me to copy metadata from one file onto several others

Basically it is not much of a problem until I finally come to run the command to set the attributes on the chosen file(s).

A typical example of the command is:

SetAttr META copyfrom:15,D:\Downloads\Images\Emma Lahana - Chris Pizzelo Portraits At  WonderCon, San Diego, March 2019.jpg

Every time I run this it attracts the error:

opus%20error

The file in the error message is indeed the file I am trying to copy to, and from when I can see of the Help files, the syntax seems correct - unless I am missing a trick - and that's pretty likely.

From the manual:

Many thanks, Leo. It wasn't quite the problem, but close enough to lead me to it.

I appreciate your swift response