Very Weird Error coming up...

[Jonathan]

When i move onto one of my maps, this error comes up.

http://i164.photobucket.com/albums/u9/r ... led234.jpg[/IMG]

I really don't get it, because it seems to be saying the multiplication function is a method... aaaghh! The line of code is this...

 #--------------------------------------------------------------------------
  # * Get Screen Z-Coordinates
  #     height : character height
  #--------------------------------------------------------------------------
  def screen_z(height = 0)
    # If display flag on closest surface is ON
    if @always_on_top
      # 999, unconditional
      return 999
    end
    # Get screen coordinates from real coordinates and map display position
    z = (@real_y - $game_map.display_y + 3) / 4 + 32
    # If tile
    if @tile_id > 0
      # Add tile priority * 32
     [COLOR=Red] return z + $game_map.priorities[@tile_id]*32[/COLOR]
    # If character
    else
      # If height exceeds 32, then add 31
      return z + ((height > 32) ? 31 : 0)
    end
  end

I would really appreciate some help with this! Cheers

EDIT: I fixed it, but i'm still interested as to why it does it. It appears that it was cause by a Priority *5 tile being used on the very bottom line of squares when your making the map. Why does this happen?

-Jonathan