The script looks correct thought I wouldn't use the Copy script step in such a script. (I'd use Set Variable.)
I suggest checking to see what values are returned by the ValueListItems function. Just a one letter difference in the value list name and you get no values returned instead of a list of values.
Just found the problem! I just read an old post dealing with FMP9 on another site
Apparently the get(FileName) function does not work when the file name has two "dots" in it. I had updated my development file to a xxxxx 2.10 & of course .fmp12. So the function does not return a file name!
And I will change the "Copy" to a Set variable command. Thank you!
A note on copy:
When a script performs the copy script step, any data the user may have copied previously to the system clipboard gets replaced by the data that your script is copying. This irritates and confuses users when they perform a FileMaker script and then the phone number they copied out of a web page or something disappears from the clipboard. By using Set variable, you can get the same job done without messing with the system clip board.