Account_ModelView_error

Traceback (most recent call last):
  File "run.py", line 3, in <module>
    from pos import app
  File "/home/zaphod/Documents/flask/pos/pos/__init__.py", line 17, in <module>
    from pos import views, models
  File "/home/zaphod/Documents/flask/pos/pos/views.py", line 68, in <module>
    admin.add_view(ModelView(Account, db.session))
  File "/home/zaphod/Documents/myProject/venv/local/lib/python2.7/site-packages/flask_admin/contrib/sqla/view.py", line 277, in __init__
    raise Exception('Model %s does not have primary key.' % self.model.__name__)
Exception: Model Account does not have primary key.