I discovered these errors when I imported the model into Poser and rendered. In the rendered images appear some parts that are black no matter the colour that I assign, in preview mode looks normal. I expand and extract the offending part of the mesh to found why is happening and the normal causes are: - Polygons with only two vertices. - Repeated vertices indexes in a face. - Duplicated faces. Poser handle very baddy these errors!

Stupidity also evolves!