Changing Tile

[sssssssssss]

PHP Code:

function fixTiles() {
  //replace tile 0xFFF,4095 with 0xAE9,2793 
  //so it doesnt block on layers
  for ( i=0; i<64; i++ ) { 
    for ( j=0; j<64; j++ ) { 
      if ( tiles[i,j] == 4095 ) { 
        tiles[i,j] = 2793;
      } 
    } 
  } 
  updateboard(0,0,64,64);
} 


Called onCreated and onPlayerEnters to make sure it happens, but nothing happens. Im finding the tile numbers with tiles(mousex,mousey). I'm probably just not applying them right, because I honestly don't get it too much. If someone could correct me and explain a little on exactly how it works? :/
Oh, just trying to replace a tile with a different tile, everywhere, for everyone, period. It will never change back. Layer issues, but if there is another way to fix the issue with using type 1 tilesets where it makes the bottom right tile def over everything else, which also makes it block, I would love to know. All it does is when it updates, it wont let you walk anymore on anything except the level you are on in gmap (thats all that has been tested).