I want to pass the value of residual(Balance) in account.invoice into another class named ip.local.

So i write an on_change function as follows.

def onchange_amount_total(self,cr,uid,ids,residual,file_no_tm,context=None):

#print file_type

print "start:::onchange_check_total"

file_no = self.browse(cr, uid,file_no_tm, context=None)

ip_obj = self.pool.get('ip.local')

ip_obj.browse(cr, uid,file_no.file_no_tm, context=None)

ip_obj.write(cr, uid,file_no,{'balance_payment':residual},context=None)

NB:.file_no_tm is a field of ip.local and it is used as a many2one in account.invoice.

       I want to change the 'balance_payment'' field with the value of residual when the value of residual is changing...