I was doing some checking and saw what I thought was an odd display of availability for YS (Perksaver) seats, but no PerkPass (YA) seats. It seemed to show up when NW/DL connections displayed through DTW on a MSP>JFK routing for 2/28/07. I'm just wondering how this could be, and if it indicates deeper problems in the credibility of what is displayed, as I always thought if a Perksaver was available on a given flight, a Perkpass was too?