Actually i try to get more in to detail with openerp. I understand the basics but in some cases it is a little confusing. So i will try to explane the Problem:

I want to add an additional module called parenteral. This Module has some special Person, e.g. agent. This agent should inherit from res.partner. To test the module i do not add an additional field, so it only has the existing fields, inherited from res.partner. In my agent_view.xml i do not inherit a form but i only created an own Form which presents the name of my agent (the only field that is required=True). There is no problem to add an save an agent. Now i change to the Module "Sales" and try to add a customer. But when i like to save the customer i get an errormessage:

field image not found in browse_record(parenteral.agent)

I dont really understand the reason because parenteral.agent should inherit all fields from res.partner.

My agent.py:

from openerp.osv import osv, fields
import time

class agent(osv.osv):
    _name = 'parenteral.agent'
    _description = 'Verwaltung der Vermittler'
    _inherit = 'res.partner'
    _columns = {}
    _default = {}
    _auto = True
agent()

My agent_view.xml:

<openerp>
    <data>
        <record id="agent_view_tree" model="ir.ui.view">
        <field name="name">parenteral.view.tree</field>
        <field name="model">parenteral.agent</field>
        <field name="arch" type="xml">
                <tree string="Vermittler">
                    <field name="name"/>
                </tree>
        </field>
    </record>

        <record id="agent_view_form" model="ir.ui.view">
            <field name="name">parenteral.agent.form</field>
            <field name="model">parenteral.agent</field>
            <field name="arch" type="xml">
                <form string="Vermittler">
            <field name="name"/>
                </form>
            </field>
        </record>

        <record model="ir.actions.act_window" id="action_agent">
            <field name="name">Vermittler</field>
            <field name="type">ir.actions.act_window</field>
            <field name="res_model">parenteral.agent</field>
            <field name="view_type">form</field>
            <field name="view_mode">tree,form</field>
            <field name="view_id" ref="agent_view_tree"/>
        </record>

        <menuitem id="menu_action_agent"
                  parent="parenteral.menu_parenteral_contact"
                  action="action_agent"
                  />
    </data>
</openerp>

Maybe someone could explane the behaviour and at most a solution.