I agree with these advices.

Hi Roeland , Thanks.
Now it`s working.
But why ?
if i just assign Diffuse color to each layer (Scene Dosn`t include any map) i cant`t have them separately in the Nod Material editor.
Does Octane Work with Layers (main file in 3d max) ?

Hi Again
I did two thins , but they didn`t work.

1- 2 different materials with 2 different colors
2 - assign UVW map to each boxes.

it`s Boring ................................ .

Hi ,
Can anyone help me about importing OBJ files and render ?

For Example When i import 4 Boxes From 3D Max and try to assign a Diffuse material to each one , it seems that 4 boxes converted to 1 object and i can`t assign 4 different Diffuse color to them.
what`s the problem? i don`t know .