entire contents of this_folder

this works in the finder


set userFolder to ("" & (path to current user folder))
set inputFolder to ("" & userFolder & "testing")
tell application "Finder"
	set theFiles to (files of entire contents of (inputFolder as alias) whose creator type is in ftypes) --	return theFiles as string
end tell

but not in folder actions script


on adding folder items to this_folder after receiving added_items
	tell application "Finder"
		set theFiles to (files of entire contents of this_folder whose creator type is in ftypes) --	return theFiles as string
 end tell
end adding folder items to

anyone have any idea why ?

Mike