[IDCS3] Error when setting PDF Export Preferences

Hi, I tried to export to PDF from ID CS3, the script is as follow:-

tell application "Adobe InDesign CS3"
	tell PDF export preferences
		set PDF destination profile to use no profile
	end tell
	tell document 1
		export format PDF type to filename without showing options
	end tell
end tell

But it prompt me an error message:
Adobe InDesign CS3 got an error: The property’s value is locked and cannot be changed.

when executing this line:
set PDF destination profile to use no profile

Please advise. Thanks!

I have figure out the problem, it happens when the field was grey-out so no input is allowed.

Now I have another question regarding PDF export preferences scripting, which I have search through ID CS3 dictionary but couldn’t find the answer.

I want to set the field of Color Conversion (as equivalent to manual setting under Output>Color>Color Conversion) to “No Color Conversion” but couldn’t figure it out.

I need your help please. Thanks!