In the past, I also saw a disparity of award tickets availability among SkyTeam partners. For example, in January, I saw an award ticket on NW that didn't show up on DL, and in summer 08 there was an award ticket on CO that DL couldn't book. Yes, I've used multiple agents, web, etc and no luck. What it turnes out to be is that an award seat could be held by specific airlines for their own passengers for as long as they wish and then be released to the "SkyTeam pool" at the airline's discreetion (if ever). One of the DL agents told me this and I verified it with DL through "my sources" .

At the end of the day a non-rev seat is a non-rev seat. They can do whatever they want with it.