核心数据版本控制，始终加载以前的版本

I have done lightweight versioning in my project, right now i have two versions and the current version is set to latest one(dataModel 2.xcdatamodel for example). I have followed every steps there in the apple document. But it's crashing every time because the old version is loading(found that after debugging, the new attributes are missing in the entity) after fresh installation. I have done lightweight versioning in my projec