I have installed calendar module and I have inherited with "calendar.event"  model...and customised one Tab in form view...then while run the server getting error "KeyError: 'calendar.event' 

Please let me know the solution..

code:

from openerp import models,fields

class Mom(models.Model):

 _inherit='calendar.event'

 agenda=fields.Text(string="Agenda")

XML:

<?xml version="1.0" encoding="utf-8"?>

<openerp>

    <data>

    <record id="mom_view_id" model="ir.ui.view">

            <field name="name">calendar.event</field>

            <field name="model">calendar.event</field>

            <field name="inherit_id" ref="calendar.view_calendar_event_form"/>

            <field name="arch" type="xml">

                <notebook>

                    <page string="Meeting Additional Info" groups="base.group_no_one">

                        <group>

                            <field name="agenda"/>

                        </group>

                    </page>

                </notebook>

            </field>

        </record>

    </data>

</openerp>