cretaed customized timesheet need to get the total minutes and hour ..but minutes are not showing in total only hour caluculated accuratly.this is my code

def amount_all(self, cr, uid, ids, field, arg, context=None):  res = {}  for order in self.browse(cr, uid, ids, context=context):        res[order.id] = {'total_line_sum': 'duration',}        val = 0        for line in order.order_line:            val += line.duration            res[order.id] = val  return res