Script that worked in CS does not work in CS4 - multiple open page, print , pdf export and close

Question

I had a script that worked great for me in Indesign CS. But now does not work in CS4. Anyone knows what needs to be done to make it work again ?
When I drop folder with indesign files on top of this script:
1. opens first page
2. turns specific layer on
3. prints using preset
4. exports using preset
5. close without saving
6. next page
Anyone who can give me solution or idea how this should work is greatly appreciated.
on open sourceFolders
repeat with sourceFolder in sourceFolders
tell application "Finder"
try
-- If you would like to include subfolders, you say - every file of entire contents of folder…
set idFiles to (every file of folder sourceFolder whose file type is "IDd5") as alias list
on error -- work around bug if there is only one file
set idFiles to (every file of folder sourceFolder whose file type is "IDd5") as alias as list
end try
end tell
if idFiles is not {} then
tell application "Adobe InDesign CS4"
set user interaction level to never interact
repeat with i from 1 to count of idFiles
open item i of idFiles
tell document 1
try
set visible of layer "ImagesTag_Layer" to true
end try
set myPreset to "letter size" -- name of print style to use
with timeout of 700 seconds
print using myPreset without print dialog
end timeout
set myPreset1 to "pdf preset name" -- name of pdf export style to use
set myName to the name -- name includes .indd should remove at some point          
with timeout of 700 seconds
export format PDF type to "users:temp:Desktop:pdf:" & myName & ".pdf" using myPreset1 without showing options -- set path here format ComputerName:Folder1:Folder2:......:FileName.pdf
end timeout
close without saving
end tell
end repeat
set user interaction level to interact with all
end tell
end if
return 10 -- try again in 10 seconds
end repeat
end open

Answer 1

(Disclaimer: me not an AS guy!)
First thing I noticed is the interaction level is set off. If you comment out this line
set user interaction level to never interact
you might be able to pinpoint the exact error -- ID will display a standard "failed" dialog, hopefully showing the line that it fails on.
A quick question: the script assumes two presets in your InDesign: one for print ("letter size") and one for PDFs ("pdf preset name"):
set myPreset to "letter size" -- name of print style to use
set myPreset1 to "pdf preset name" -- name of pdf export style to use 
Do these actually exist in your CS4, with the same (non)capitalization and spaces?