Thanks guys, for your advice! They are always very helpful! I need help once again. I can not insert an object, more than once. Light poles, houses, spectators, trees, whatever the object. It show me a strange message, like: error ... bla bla bla ... Maybe because I do not know to use the "edit objects" properly! For example: I would like to add the grass, or a group of trees in a specific area of the terrain. Or, a row of different trees. How can I do?