The following domain addition throwing a error while using department_id field in search view.

And tried the openerp doc doc.openerp.com/v6.0/developer/2_6_views_events/views/search_view.html#fields

How can i solve this?

<field name="type">search</field>            
<field name="arch" type="xml">
   <search string="Home">
          <field name="company_id"/>
          <field name="department_id" domain="[('company_id','=',company_id)]"/>
   </search>
</field>

Thanks in advance