public function validatePayment()
    {
        // Remove payment methods initialization data from session of any is set
        $this->_unsetSessionInitData();

        $mReturn = $this->_OxpsPaymorrowPayment_validatePayment_parent();

        if ($this->_isPaymorrowPayment(oxRegistry::getConfig()->getRequestParameter('paymentid')) and
            $this->_isPaymentResponseSessionInvalid()
        ) {
            oxRegistry::getSession()->setVariable('payerror', 1);

            return null;
        }

        return $mReturn;
    }