Print single plate Applescript

The following script will turn off all plates (colors) except the one spot, open the print dialog, and the resulting .ps file will have only one spot color.
However if I include "print without dialog" I get all plates.
Any thoughts on why/how to avoid getting all plates

tell application "Adobe InDesign CS3"

tell active document


tell print preferences
-- set other properties for example, active printer style

set color output to separations

set printer to postscript file
set PPD to "Xerox DocuColor 2006"

set print file to "Chaco:Users:tpetrill:Desktop:TEST2.ps"
end tell
end tell
set print ink of ink "Process Magenta" of document 1 to false
set print ink of ink "Process Cyan" of document 1 to false
set print ink of ink "Process Yellow" of document 1 to false
set print ink of ink "Process Black" of document 1 to false
-- set print ink of ink "RF.tp" of document 1 to true


tell active document
-- print without print dialog
end tell


set print ink of ink "Process magenta" of document 1 to true
set print ink of ink "Process Cyan" of document 1 to true
set print ink of ink "Process Yellow" of document 1 to true
set print ink of ink "Process Black" of document 1 to true



end tell