cocos creator插件在scene-script里面加载资源出错

cc.loader.load({type:“uuid”, uuid:“a4c5b53e-030d-4bf8-9e7d-ee2a1163428a”}, function (err, _obj) {
if(!err && _obj){
var item_node = new cc.Node();
var _sf = item_node.addComponent(cc.Sprite);
_sf.spriteFrame = _obj;
this.loadResSucc(item_node,map_width,map_height)
}
}.bind(this))
sf.spriteFrame = _obj;的时候报spriteFrame.textureLoaded is not a function.这个错是为啥