public function execute()
    {
        parent::execute();

        date_default_timezone_set("UTC");
        $dateFormat = 'Y-m-d\TH:i:s.00\Z';
        $current = new DateTime();
        $currentTime = $current->format($dateFormat);

        HpsInputValidation::checkDateNotFuture($this->startDate);
        HpsInputValidation::checkDateNotFuture($this->endDate);

        $xml = new DOMDocument();
        $hpsTransaction = $xml->createElement('hps:Transaction');
        $hpsReportActivity = $xml->createElement('hps:ReportActivity');
        $hpsReportActivity->appendChild($xml->createElement('hps:RptStartUtcDT', $this->startDate));
        $hpsReportActivity->appendChild($xml->createElement('hps:RptEndUtcDT', $this->endDate));
        $hpsTransaction->appendChild($hpsReportActivity);

        return $this->service->_submitTransaction($hpsTransaction, 'ReportActivity');
    }