Problem with TMXTiledMap on Firefox

I’m struggling with Firefox and TMXTileMap, I have a level.tmx / tileset.png working fine with cocos simulator and also with Chrome, but with Firefox I get a null map (this._map is null)**.
Is not a null map, but it has no children, no properties values (all is 0 or “” or null).

Why? Hope someone can help me… I don’t know if I need to post more code, but I just want to add the map.

var res = {
   Tileset_png : "res/levels/tileset.png",
   level_tmx : "res/levels/level.tmx"
};
       
var Game: cc.Layer.extend({
_map:null,

onEnter:function(){
this._super()
this._map = new cc.TMXTiledMap(res.level_tmx);
this.addChild(this._map);

var props = this._map.getProperty("MyCustomProperty");
var levelInfo = JSON.parse(props);
)}

Found the problem. Was an inexistent file in the resources variable.