Probably someone already asked this question, but probably that my terrible English does not allow me to find it on the forum. I loaded cell muldraugh map in TileZed. Then I decided to clear a spot on the map for the new building. But when I tried to erase the BMP eraser part of the tree and the grass, I was disappointed. Because grass and trees refused erased. I also tried to create a new layer above the standard, but it did not help ... How to deal with it, I might do something wrong?