I've installed odoo 9 on a ubuntu 12.04 system. I have the error below while creating the first database

ParseError: "Mixing apples and oranges: None in res.groups(19, 20)" while parsing /odoo/odoo-server/openerp/addons/base/security/base_security.xml:18, near

<record model="res.groups" id="group_system">

<field name="name">Settings</field>

<field name="implied_ids" eval="[(4, ref('group_erp_manager'))]"/>

<field name="users" eval="[(4, ref('base.user_root'))]"/>

</record>

I'm i missing something ?