Originally Posted by Airfrancefan
it is with 074. but booked thru a travel agency, if that makes any difference
This is strange.
As far as I've been told, once a flight opens for check-in, all e-tickets are eligible for online check-in, irrespective of the airline whose ticket stock is used (012 for NW, 074 for KL, 057 for AF etc).
However, this may not apply to the search function in the reservation system (so before the 24-hour window for US destinations)
The NWA online checkin accepts both a reference number (PNR or record locator) AND e-ticket number (you can change the option by clicking on the button) so you should be fine.
Good luck, have a good flight!