Custom Payment Method, problem with cancellation of orders

$this->modifyOrder($order_id, $this->payment_params->invalid_status, true, true);

		if($vars['EXECCODE'] != 0000)
		{
			
			// Here we display debug information which will be catched by HikaShop and stored in the payment log file available in the configuration's Files section.
			//print "EXECCODE is non-zero";
			if($this->payment_params->debug)
				print 'payment '.$vars['MESSAGE']."\n\n\n";
				
			// This function modifies the order with the id $order_id, to attribute it the status invalid_status.
			//$this->modifyOrder($order_id, $this->payment_params->verified_status, true, true);			
			$this->modifyOrder($order_id, $this->payment_params->invalid_status, true, true);
			
			//To redirect the user, if needed. Here the redirection is useless : we are on server side (and not user side, so the redirect won't work), and the cancel url has been set on the payment platform merchant account
			$this->app->redirect($cancel_url);
			return false;
		}
		//If everything's OK, the payment has been done. Order is validated -> success
		else
		{
			//print "All OK";
			$this->modifyOrder($order_id, $this->payment_params->verified_status, true, true);
			
			$this->app->redirect($return_url);
			return true;
		}

	$qrystr = $_SERVER["QUERY_STRING"];
	$actionok = "http://unicomms-emall.com/index.php?option=com_hikashop&ctrl=checkout&task=n"."otify&notif_payment=unicommspayment&tmpl=component&".$qrystr;
	$actionnok = "http://unicomms-emall.com/index.php?option=com_hikashop&ctrl=order&task=cancel_order&".$qrystr;

if ($_REQUEST["choiceLst"] == "Ok")

	if ($_REQUEST["choiceLst"] == "Ok")
	{
		$actionurl = $actionok . '&EXECCODE=0000'; //Signifies that the trasaction is okay
	}
	else
	{
		$actionurl = $actionok . '&EXECCODE=9999'; //Signifies that the transaction is rejected
	}