private function createConnection()
 {
     if (is_null($this->lotteryType) or is_null($this->raffleDate)) {
         throw new ResultParameterException('Lottery type and/or raffle date parameter null, use set parameter with this class setOption method');
     }
     return new MpiConnection(new ConnectionConstants(ConnectionConstants::getConstant($this->lotteryType)), $this->raffleDate);
 }