Yep, that appears to be the problem... didn't realize KVS used the NWA engine. Are there any plans to move it to the DL engine since NWA will be going away eventually?

I've found the DL engine to be very accurate on one way segments (but, not so good at piecing together multiple segments) for DL & NW flights as well as quite a few partners (AF and KLM for transatlantic). I threw together a scripting interface for the DL award engine that searches several (as in 35-40) segments on a regular basis (with alerts) to try and build a saver itinerary. It's sad I have to resort to that to try and find an award ticket, but it sure is a lot simpler (and quicker) than testing every leg manually!