Scenery altitude problem

Hi and thanks to all responders..............I installed FSX gold to my new computer and loaded up Dream Team JFK and Imagine sim KLGA...I then took a flight and noted that in patches the default scenery was flashing through....For JFK when I was high enough all you saw was the Dream Team scenery for KLGA you still saw the broken up runway taxi ways and gates..........any help to get this right would be much appreciated....

Thanks Again