InDesign CS4 - problem relinking placed PDFs

I regularly receive PDFs that do not fit a specific template. I have created an INDD document in which I repositioned and resized parts of a placeholder PDF, in order to fit the template (the placeholder PDF is placed six times in the document). When I receive a new PDF, I run a droplet which replaces the placeholder PDF by relinking to the new dropped PDF.

The following script works fine for CS3, but in CS4, the PDFs are relinked at 100% and in a default placement, instead of the size and position saved in my template document.

I have posted the subroutine for processing files:

on process_item(this_item)
	tell application "Adobe InDesign CS4"
		set TRI to open "Location:TRI.indd"
		tell TRI
			set myLinks to links whose name is "ReplaceMe TRI.pdf"
			relink myLinks to this_item as alias
				update myLinks
			end try
		end tell
	end tell
end process_item

Model: G5
AppleScript: 2.0.0
Browser: Safari 4.0.3
Operating System: Mac OS X (10.5)