Print Preset Applescript works on Mac Pro - not iMac

I am trying to print an InDesign document on 3 part NCR Tabloid size, using the printer’s manual feed tray.
I created an InDesign Print Preset named “WorkOrder” and also a Print Preset “WorkOrder” using the printer’s driver.

Here is the code snippet that works on my Mac Pro running 10.7.5, but doesn’t work on an iMac running 10.7.5 (mirrored settings and both using the same printer):

set workOrder to pathtoInDesignfile

			-- change Printer Preset to WorkOrder:
			do shell script "defaults write WorkOrder; defaults write 4"
			tell application "Adobe InDesign CS6"
				print workOrder using "WorkOrder" without print dialog
			end tell
			tell application "Adobe InDesign CS6"
				close workOrder saving no
			end tell
			-- change Printer Preset back to Default:
			do shell script "defaults write Default; defaults write 1"

This script runs on the iMac, but only outputs 1 - Letter size page.

Model: Mac Pro
AppleScript: 10.7.5
Browser: Safari 536.29.13
Operating System: Mac OS X (10.8)

I’ve never scripted setting the default printer using shell, that seems sort of “unreliable” to me. I script InDesign all the time. Why not just mirror your settings but set the printer in the preset?

make printer preset with properties {name:"MyPrintPreset", printer:"MyFavoritePrinter", PPD:"MyPrinterPPD", crop marks:false, bleed marks:false, registration marks:false, page information marks:true, use document bleed to print:false, include slug to print:true, paper size:custom, color output:composite CMYK, send image data:all image data, font downloading:complete, download PPD fonts:true, PostScript level:level 3, data format:binary, source space:use document, profile:use document, flattener preset name:"[High Resolution]"}


tell application "Adobe InDesign CS5"
					tell theDoc
						tell print preferences
							set active printer preset to myCurrentPrintSetting
						end tell
					end tell
				end tell