Grimrock: Plate Path Puzzle

-- insert name of door within quotes
door = "puzzle_door"

-- insert names of plates, in order, within brackets
plates = {  "puzzle_plate_a_5",
        "puzzle_plate_a_6",
        "puzzle_plate_a_5",
        "puzzle_plate_a_2",
        "puzzle_plate_a_1",
        "puzzle_plate_a_4",
        "puzzle_plate_a_1",
        "puzzle_plate_a_2",
        "puzzle_plate_a_3",
        "puzzle_plate_a_2" }

counter = 0
last_plate = nil

for i = 1, #plates do
    for j = 0, i - 1 do
        if plates[i] == plates[j] then break end
        if j == i - 1 then
            hudPrint(tostring(plates[i]))
            local plate = findEntity(plates[i])
            plate:addConnector("activate", self.id, "isPressed")
            plate:setTriggeredByParty(true)
            plate:setTriggeredByMonster(false)
            plate:setTriggeredByItem(false)
        end
    end
end

function isPressed(plate)
    if last_plate == plates[counter] and plate.id == plates[counter + 1] then
        counter = counter + 1
        if counter == #plates then findEntity(door):open() end
        last_plate = plates[counter]
    else
        counter = 0
        last_plate = nil
    end
end