Thanks SamPage.
I am very late to answer you because I did not have much time right now. I understand better and will test this, but I need to update before rhino 4 (should I use SR8-SR9?).
In fact I had originally downloaded the source files (in .rvb) and did not understand how and where to place ... But it's ok now.
To be honest I can't use octane since I bought it (5 licenses) because unable to move and change the textures in octane. Rhino is not suitable for this, one can place basic textures but it's really not practical.
So thanks a lot for your help