I'm trying to send email from code like this in a custom addon when i push a button on a Purchase Order form, there is only a problem... body result empty... i can't undestand where is the error... Anyone can help me?

def req_aut(self, cr, uid, ids, context=None):
    pur_ord = self.read(cr, uid, ids, ['name'], context=context)[0]
    subject="subject: "+ pur_ord['name']
    body="body" 
    message_obj = self.pool.get('mail.message')
    email_to=[]
    email_to.append('a@a.it')
    msg_vals = {
        'subject': subject,
        'date': time.strftime('%Y-%m-%d %H:%M:%S'),
        'user_id': uid,
        'body_text': False,
        'body_html': body,
        'email_from': 'appo@appo.it',
        'email_to': email_to,
        'subtype': 'html',
        'state': 'outgoing',
        }
    msg_id = message_obj.create(cr, uid, msg_vals, context)