Originally Posted by booker_26
However, when I try to recreate the same itinerary on CO.com I can't pull up the same flights. They exist in the online schedule but the reservation engine refuses to find the appropriate flights. This might be a stupid question, but is there a reason why CO.com won't allow reservations on certain codeshares (it always diverts me to CO metal routings)? I try to book all my CO flights through CO.com for the bonus miles and keep all my intineraries in one place, but looks like CO.com only likes routings that include CO metal.

I had a very similar experience a few months ago when booking IAH-ATL-IAH on co.com. Outbound was on CO metal. I needed a late return flight, and the best time was on a codeshare. (I forget which carrier it was - not DL - possibly one of their smaller airlines.) It showed up on the timetable, with a CO codeshare flight number, but would not show up on co.com to book it, no matter what I did or how I rigged things.
Frustrated, I finally got on the phone. First I called the Technical Support Desk, because I figured it had to be a technical problem. The tech support guy told me it should show up and he was going to put an order in to get it fixed.
I fiddled around with it a bit more, and still couldn't get it to work. I decided to phone the reservations folks to see if I could get them to help. (Several years previously when co.com wasn't showing something properly, they booked a flight for me and gave me the online booking bonus anyway.) The reservations agent told me co.com would only show flights on CO metal. End of discussion. I asked her why and she told me they didn't want people flying on any other carrier, because they lost money that way, so co.com would only show actual CO flights.
Somehow that just doesn't seem right. Very frustrating.