Creating cube map using Vray

[Deetee]

hello guys...

i have an interior scene which i wanted to bring it into unity3D for real time walk through...

 

now im trying to create a cube map for my interior in unity3D to have some reflections on it...

 

this is my 1st time trying to create a cube map from 3ds max.

i followed the tutorial here

http://wiki.polycount.com/CubeMap

 

but unfortunately the cube map that i rendered out seems to be all overexposed.

i assume that this method is only for normal 3Ds max rendering that using normal camera to render....

and as for my scene, im using Vrayphysicalcamera, vraysun, and vraysky for my rendering. i guess this is the issue caused the tutorial method doesnt work in my scene...

 

so can anyone here enlighten me what approach should i take to create a proper cube map for my interior scene?