context_tz in res.users problem

If I call a function like this:

        report_xml_pool = self.pool.get('ir.actions.report.xml')
        report_ids = report_xml_pool.search(cr, uid, [('report_name', '=', 'fattura')])
        report_service = 'report.' + report_xml_pool.browse(cr, uid, report_ids[0], context).report_name
        service = netsvc.LocalService(report_service)
        (result, format) = service.create(cr, uid, ids, {'model': 'account.invoice'}, context or {})

I obtain this error:

  File "/home/opencode/openerp/7/addons/report_aeroo/report_aeroo.py", line 768, in create
    context['tz'] = pool.get('res.users').browse(cr, uid, uid).context_tz
  File "/home/opencode/openerp/7/server/openerp/osv/orm.py", line 488, in __getattr__
    raise AttributeError(e)
AttributeError: "Field 'context_tz' does not exist in object 'browse_record(res.users, 1)'"

If I go in the table res_user the field context_tz doesn't exist.

VERSIONS:

OPENERP 7

SERVER: 5099
WEB: 4035
ADDONS: 9519
AEROO REPORTS: 5