Why? Poser's inability to deal with things, basically. Poser has alot of shortcomings when it concerns imports and exports. Unlike Vue, and most other 3D rendering programs, Poser was made more for dealing with it's own meshes, and not imports. Poser has a problem with meshes, and how it displays and renders them. Short of remodeling (or fixing problem areas) and remapping the objects to accomodate Poser, there's really nothing you can do about it.