[LayaAir 2.0]Pool 使用 Laya.Prefab

public targetBox:Laya.Prefab;

let box: Laya.Sprite = Laya.Pool.getItemByCreateFun("ItemBox", this._control.targetBox.create, this._control.targetBox);
运行报错: Cannot read property 'create' of undefined
targetBox又在 control里面引用一个Prefab