HELP! Problem with meshes.

First of all, I apologize for my English, if you do not understand something, ask me and I will explain better (my English is not so good).

  I’m trying to learn how to export meshes from second life, for share them. I’m using MeshesSL. I followed the procedures found on the web, and I seem to do things the right way, but when I try to import them into the game to test them, they appear deformed, and I get an error message (see screenshot below).
Does anyone know why this happens?

Download from Source link