Booked open jaw on the AC website - got all the way through including providing cc number and then it failed with the "There is a problem...please call..." message. Called SE Reservations and it turns out that the problem resulted from the fact that the options provided online included connections that were codeshares - e.g. LH but operated by LO and SN but operated by LX and evidently the website could not handle that. Trip was priced correctly however. Took the phone agent about 20 minutes to manually construct the itinerary and ticket it - he had to use LO and LX flight numbers for it to work.