Yeah, this is one of the most frustrating, and I think misleading, aspects of codeshares and indeed the whole "Skyteam" alliance. It frustrates me to no end that CO and DL/NW may have a codeshare that goes end-to-end on DL/NW metal, but heaven forfend you try to book it through Continental. While I understand that CO doesn't want us to all defect to the lovely DL/NW products and still get miles - what's the point of having codeshares if you can't use them?