Django. You don't have permission to edit anything

I created a little app a while ago. I created admin.py and used admin.site.register(MenuEntry) to add the class to admin console. It showed the items of that class just fine. Then I began working on another app and created everything as before. But now it says: You don't have permission to edit anything. I compared files from that and from this apps and they look quite similar, so I just can't find the difference and I can't realize what to do now to make it work.