This is my error, any help please

ERROR

    raise ValueError('No such external ID currently defined in the system: %s.%s' % (module, xml_id))

    ValueError: No such external ID currently defined in the system: purchase_rentals.action_extend_rent

Here my code:

        (extend_rental_view.xml)

                .

                .

                .

<record id="action_extend_rent" model="ir.actions.act_window">

<field name="name">Extend Rental</field>

<field name="type">ir.action.act_window</field>

<field name="res_model">extend.rental</field>

<field name="view_type">form</field>

<field name="view_mode">form</field>

<field name="view_id" ref="extend_rent_form"/>

<field name="target">new</field>

</record>

<act_window id="action_extend_rent"

                name="Extend Rental"

                res_model="extend.rental"

                view_mode="form"

                target="new"/>

                .

                .

                .

 

(__init__.py)

.

.

.

import wizard

(__openerp__.py)

.

.

.

'data' : [

              'rental_view.xml',

              'purchase_view.xml',

              'wizard/extend_rental_view.xml'

              ],

.

.

.

 

(rental_view.xml)

.

.

.

<button name="%(action_extend_rent)d" string="Extend Rental" type="action" states="manual" class="oe_highlight"/>

.

.

.