help with this khan academy exercise I do not know what the error means

/ the error tells me: Mmh ... the onClick method should only ignore the invalid spins on the boxes that are not empty, but it seems that your method is doing something else / cat game

var playerTurn= 0;
var NUM_COLS=3;
var NUM_ROWS=3;
var SYMBOLS=["X","O"];

var tiles = [];

var checkWin = function() {

};

var Tile = function(x, y) {
    this.x = x;
    this.y = y;
    this.size = width/NUM_COLS;
    this.label = "";
};

Tile.prototype.draw = function() {
    fill(214, 247, 202);
    strokeWeight(2);
    rect(this.x, this.y, this.size, this.size, 10);
    textSize(100);
    textAlign(CENTER, CENTER);
    fill(0, 0, 0);
    text(this.label, this.x+this.size/2, this.y+this.size/2);
};

Tile.prototype.empty = function() {
    return this.label === "";
};

**Tile.prototype.onClick = function() {
     if (!this.empty()) {
     Tile.draw();
    }

    this.label = SYMBOLS[playerTurn];
    playerTurn++ ;


    if ( playerTurn >= SYMBOLS.length) {
        playerTurn  = 0;
    }**

    // If the tile is not empty, exit the function

    // Put the player's symbol on the tile

    // Change the turn
};

Tile.prototype.handleMouseClick = function(x, y) {

   if ( x >= this.x && x <=this.x  +this.size   &&
        y >= this.y && y <= this.y +this.size)
    {
        this.onClick();
    }

    // Check for mouse clicks inside the tile
};

for (var i = 0; i < NUM_COLS; i++) {
    for (var j = 0; j < NUM_ROWS; j++) {
        tiles.push(new Tile(i * (width/NUM_COLS-1), j * (height/NUM_ROWS-1)));
    }
}

var drawTiles = function() {
    for (var i in tiles) {
        tiles[i].draw();
    }
};

mouseReleased = function() {
    for (var i in tiles) {
        tiles[i].handleMouseClick(mouseX, mouseY);
    }
};

draw = function() {
    background(143, 143, 143);
    drawTiles();
};