You need to have a Program and make sure you have set either Per user login code or Per user phone as the authentication method for the Program. This needs to be done in order to identify each user uniquely.
MAPPING FROM QONDOR ADMINWEB
In a project with Check-in enabled you can map wristbands (RFID check-in code) to your attendees in the Participants module. This is a great way to give your VIPs an extra service or if you have a small project where you are able to provide this service to all your attendees. After mapping a wristband (RFID check-in code) to an attendee, make sure you mark it well (e.g. in an envelope with the attendee name). Here's how you map:
In Participants, click Check-in information to open the dialogue box.
From Check-in information you can set or replace an existing check-in code. If you have uploaded a list of check-in codes, this field will validate the code upon saving.