It's possible you have another (older) copy of the Esellerate engine installed by another product that use it, check for the following file:
Esellerateengine.dll
In the following locations:
1) Your FS9 root folder
2) The main C:\Windows folder ( if this is your Windows folder )
3) The C:\ProgramData\Esellerate folder
If you have this .DLL in your FS9 root folder or your C:\Windows folder, REMOVE IT, because it's the wrong location for Vista/Windows 7 and, also, it's probably the wrong (old) version of the .DLL that has been put there by another product that uses the Esellerate engine DLL.
You should have one and only one copy of that .DLL and, on a Vista/Windows 7 system, it should be located at C:\ProgramData\Esellerate, which is where our installer puts it.
When you removed all the versions, reinstall the scenery again.