Hi my name is Alex Makoviecki. I recently got the PMDG 737NGX and I really... really love it! The only problem I have with it is descending. I am about thirty miles back from the TOD (top of descent) and I set in the altitudes in the FMC that I should be at for each waypoint and VOR for the OMN.HILEY2 STAR at Miami Intl. I was using a chart that shows you the altitudes for each waypoint and VOR. I then set the altitude for descent to 5000ft which was the altitude for one of the waypoints that I would descend to and stay at for a while until descending to the glideslope intercept altitude. When I reached the top of descent the engines went to idle and the aircraft started descending but then leveled out at 37000ft (my cruising altitude was 38000ft). I noticed that the FMC had a message that said DES PATH UNACHIEVABLE, that was weird because I set the right altitudes for each waypoint and VOR for exactly what they should have been. I got the aircraft to descend a little more by copying of the speed and altitude of the first descent waypoint and pasting it again on the same waypoint. But I only got the aircraft to descend to 32000ft. I also noticed that when I am climbing above 25000ft the aircraft slows down the climb to 1000fpm, compared to 1800fpm in other payware aircraft. I would appreciate some help here!Thanks,Alex.