Have you read the "Read-me" instructions which came with the download?
Many Scenery add-ons require additional Objects and Textures to be installed from other sources as well...and these must be placed in the correct Folder(s)...

...!
Some scenery requires an additional Tree Set to be installed..(Gerrish Grey, etc)
.....and some scenery will only display fully if the user has certain Scenery Design programs installed, (eg: LAGO FSE/FSSE, etc, containing the required Objects and Textures).
F....G-BPLF.... 8-)...!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.