If you are using your (headphone jack) credit card swiper for the first time using iOS9, be sure to allow the swiper to access your device's microphone. When you plug in the credit card swiper to your headphone jack and open the Ticketleap app, you will be prompted to allow or do not allow the swiper to access your microphone. Please be sure to press allow. If you press do not allow, the swiper will never fully power up and you will receive an error message.
If you did press do not allow don't worry, you can fix it! On the mobile device go to Settings > Privacy >Microphone to allow the swiper to work on your iOS device. After making the changes, reload the Ticketleap app and you can swipe away!