[TypeError: this.gameMap.layerNamed is not a function] dont know why?

cocos2d-x JavaScript
#1

[TypeError: this.gameMap.layerNamed is not a function] when I run
but these is [JSBool js_cocos2dx_CCTMXTiledMap_layerNamed(JSContext cx, uint32_t argc, jsvalvp)] in jsb_cocos2dx_auto.cpp