My python code is put  in  a  file  res_users.py :

class Users(models.Model):
    _inherit = 'res.users'
    _description = "Users and the properties he handles"
   facades = fields.Char('Facades')

Then  I type  ./odoo/odoo-bin --addons-path=./custom,./odoo/odoo/addons -d rd-demo -u res_users --dev xml

 when I upgrade the module, I got the following error message:

psycopg2.errors.UndefinedColumn: column res_users.facades does not exist
LINE 1: ...share", "res_users"."company_id" as "company_id", "res_users...

This is quite confusing. I though _inherit tells odoo that I want to extend the model res.user by adding one more field. What did I missing so that odoo though my inheritance does not take effect?