I work with Bob Track Builder, then export to rFactor format, and then import in 3D Studio Maxi with the script GMT2 Importer. All perfect here.
The problems become with the multimaterials. So netkar-pro editor don't admit multimaterials, I have a script (Detach by ID) to convert this multimaterials in single materials, but I have problems.
That is the message of the error.
Also if I check "Use Prefix" on the script and type a name, when I click on DETACH, give the same error but stop the code in other line.
I think the problem is with the gMaterials that are using shaders from rFactor, but I'm not sure, I don't know so much about 3d Studio