I want to print a report. I have a module named partnership is under the addons folder. and under the partnership folder I carry the folder that contains new_report.rml new_report.sxw and new_report.py class containing this code:

import time
from openerp.report import report_sxw

class new_report(report_sxw.rml_parse):
def __init__(self, cr, uid, name, context):
super(new_report, self).__init__(cr, uid, name, context=context)
self.localcontext.update( {'time': time,})

report_sxw.report_sxw('report.commercial_report', 'contratcommercial',
'partnership/report/new_report.rml',
parser=new_report, header="internal")

under addons / partnership partnership I report.xml containing this code:

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
<data>
<report
auto="False"
id="new_report_id"
model="contratcommercial"
name="commercial_report"
rml="partnership/report/new_report.rml"
string="imprimer contrat "/>

</data>
</openerp>

but I still have this error 

report.commercial_report

(<type 'exceptions.KeyError'>, KeyError(u'report.commercial_report',), <traceback object at 0x06F19DC8>)

I even tried to put an empty file to know if the error is because of rml file but no result and always the some error

please any help