Hi Cecil, most likely Rhino v4 created a particular kind of "point cloud" entity when you imported the point file. Right now MoI only looks for individual point entities and does not handle that "point cloud" object type.

If you run the Explode command in Rhino it would probably convert the point cloud into individual point objects and that would then work saving as a 3DM file type - when you export to a v2 3DM it basically does the explode step for you right then automatically.

- Michael