i have added a button wizard in purchase order form that contain reject button and special cancel button.

as soon as i click that button , the wizard form show up. Then after i fill every field in that wizard i have to click the reject button to execute the method. but my method doesn't return anything. did i put the wrong return ?

here's the code :

class reason_reject_approval(osv.osv_memory):
    _name = "reason.reject.approval"
    _columns = {
                'reason':fields.text('Reason')
                }
    
    def wtc_reject_approval(self, cr, uid, ids, context=None):
        val = self.browse(cr, uid, ids, context=context)
        user = self.pool.get("res.users").browse(cr, uid, uid)['groups_id']
        line = self.pool.get("purchase.order").browse(cr,uid,ids,context=context)
        
        for x in line.app_line :
            for y in user:
                    if y == x.group_id :
                        for z in line.app_line :
                                z.write(cr,uid,z.id,{
                                        'reason':val.reason,
                                        'value':line.amount_total,
                                        'sts':'3',
                                        'pelaksana':uid,
                                        'tanggal':datetime.today()
                                        })   
                                
        self.pool.get("purchase.order").action_cancel(cr, uid,ids)
        self.pool.get("purchase.order").write(cr, uid, ids, {'approval_state':'r'})
                                                      
        return True

--------------------------------------------------------------------------------------------------------------------------------------------------------------------

do you know how to solve it ? thanks.