This applescript runs on 2 of my 3 Macs: whats the story?

OK, so this is part of a script embedded in filemaker.
It works on my 2 newest machine (acquired in the last 6 months) but not on the oldest which is about 3 years old running El Capitan with word up to date.
Am I missing some obvious patch or what?

tell application "Microsoft Word"
	open thetemplate
	save as active document file name doccc
end tell

doccc is defined earlier in the script