Hi Raymond, yes like Pilou says the problem you've got there is you have many faces that have more than 4 edges. A sub-d model needs to have things divided up into smaller elements than that, it has to be made up of quad polygons not like your structure.

A model like you show there with lots of planar areas is better to do in NURBS than in sub-d anyway, just select what you've already built and run the Construct > Fillet command to smooth off its edges rather than trying to do sub-d on it:





- Michael