I have this in my models:

# -*- coding: utf-8 -*-
from openerp import models, fields
 class event_event(models.Model):
 _inherit = ["event.event"]

 
 testing = fields.Char('test')  

and this in my view:

<record model="ir.ui.view" id="res_partner_view">
     <field name="name">res.partner.form</field>
     <field name="model">res.partner</field>
     <field name="inherit_id" ref="base.view_partner_form"/>
     <field name="arch" type="xml">
     <xpath expr="//notebook[last()]" position="inside">
         <page string="My_New_Tab">
             <field name="testing"/>
         </page>
     </xpath>
     </field>
 </record>

Odoo is still giving me this:

Error details: Field `testing` does not exist

why?