OBJ Files From Rhino

[Robb63]

Wondering if you can help. I am exporting mesh data from Rhino as an OBJ file. It is organized in Rhino so that like colored parts are on individual layers and the mesh data is set to assign material by layers.
When I bring it into Keyshot each part takes color separately and seems to ignore the layers it is assigned to.
Is there some magic tick box I've got set wrong?

[guest84672]

Make sure to export material definitions.

Thomas