InDesign Server CC - AppleScript - activate document

We have an issue to run our AppleScripts with the CC version. It seems that something has changed regarding how to activate ("talk to") a document in InDesign Server CC.

This script changes the behaviour of printing inks in ink manager. With CS5, it runs, with CC i got an error.

tell application "Adobe InDesign Server"

    activate

    set myDocument to document 1

    tell myDocument

        set docInks to inks

        repeat with x from 1 to count docInks

            if is process ink of item x of docInks is false then

                set convert to process of item x of docInks to true

            end if

        end repeat

    end tell

end tell

I assume the line

set myDocument to document 1

works no longer.

Which is the right expression?