I do not understand the problem, I have always done so...
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I have solved, somehow...
(Note: ZM2 does not give all the necessary data for map objects.
At the end of prelight must attach the object map to an object map of SA,
to which is assigned the default material, then it can be easily erased).
To run prelight use the latest version, ZM2 226, 993 Build.
This version works in reverse of the above,
that makes dark the object; so if you already black, nothing happens...
Go to "Options/Settings", and change "Ambient Light" from black to white:
https://s26.postimg.org/byobjd4ft/prelight1.jpg
A map object is different from the other 3D, weapons, vehicles and peds, as regards the management of the vertices:
https://s26.postimg.org/mms2i7eex/prelight2.jpg
Now the object is full of light:
https://s26.postimg.org/9wnu546gp/prelight3.jpg
The prelight making projection from the "Perspective" or "User" view, selecting the leaders concerned.
I do not recommend performing prelight of all vertices, because those behind did not receive light.
To perform the cube prelight of all vertices:
https://s26.postimg.org/sqe8fuu2h/prelight4.jpg
Press left clik mouse to the desired level of light:
https://s26.postimg.org/aov3i201l/prelight5.jpg
Mapping objects have 2 prelight, for the day and for the night.
To handle the light at night, it click "Swap colors":
https://s26.postimg.org/pyuyp8vjt/prelight6.jpg
Let's change the light from tentende to yellow to tending to blue, for external objects:
https://s26.postimg.org/x3crya2t5/prelight7.jpg
To sum it all.
ZM2 could reverse the day/night cycle, check in game this.
