Quote: "Sorry for my english ..."
I'm sure it's better than my Italian!
OK, when you load your "Piliere_9.x" object it automatically loads the texture "Piliere_9.jpg". When you texture an object in Dark Basic Professional you can assign the material to texture "stages", Dark Lights uses one of these stages for the ligh-map images it creates (I'm sorry I'm not sure which).
What I think is happening in your model is that the texture stage Dark Lights is applying the light-map texture to is the same as the 'stage' you have applied the wall texture to when you made your model.
I hope this helps... I could be wrong though!