This is frustrating the hell out of me now. I've just flown a route and from Heathrow to Edinburgh and it followed the route precisely, put me on a perfect landing approach to the poin t where I just had to hit the APP button and it guided me down perfectly. The ONLY thing that is confounding me at the moment is that I can't get the FMC to display the Top of Climb or the Top of Descent, hence the plane will not descend to the correct heights automatically. I don't know what I'm doing wrong as I had to hit the V/S button and arbitrarily decrease my height and rate of drop. Its totally baffling. I set me cruise alt on the MCP and it climbs to that fine, when I've reached say FL280 (my max height) I reduce the alt to 3000 which is my next low point - it stays on ALT HOLD but then doesn't automatically switch over at the Top of Descent....because somehow the FMC has not got it programmed in. Not sure what I'm doing wrong. Using the stock plane, may be better using the Zibo mod.