FSD Aerostar Pressurization

Hi Everyone,I'm taking a break from FSX and enjoying flying some of my old favorites in FS9. One of these is the FSD Aerostar, but for some reason, I can't get the pressurization to work. Air valves on, cabin door sealed, rate set, but the cabin pressure climbs past the selected altitude, right with the aircraft altitude. I'm not getting the warning light on the panel above 10,000 ft, just the gauges indicate no pressure. I did install the update FSD provided last April, but no change to the pressurization.I checked the FSD support forum, and others are having the problem also, but the best FSD came up with is to follow the checklist (I did). Has anyone on this forum had this problem and found a work around?Dale