Terrain, brush muvement ...

Ok, i am new of this fantastic software, and probably i have surely make 1 error .

I have make a 3d simulation of a town, really semplified.
For the areas with terrain i have try to remove the 3ds mesh to replace it with a terrain created inside Unity.
The special terrain editor into Unity is not applicable to 3DS imported, and i want use the special 3D-grass editor and paint grass editor.
To eliminate visual defect of 3DS+terrain, i put the zero level of 3DS is into Y=0 global axys and the zero level of the terrain created with Unity at Y=-0.2.

The brush 3d created with the terrain editor moves it. See this:
http://giandgi.altervista.org/prova_terreno_-_erba_oscilla.avi
What error i have make?

thanks for help
bbye

The 3D paint tool only works on a unity terrain, not imported objects. Sorry.

Did I get that right? Spelling and some grammar might help me understand a bit better. I noticed your broken link brought me to a spanish page. If I offended you by saying this (as english was not your first language) my apologies.