Don't worry, this seems to be a problem lots of users are experiencing. Follow the steps below and it will fix the issue
1. Go to your settings app > General > Date and Time > Set Automatically to off.
2. Select the date one year ahead.
3. Go back to the Passbook app and try again. This should fix it.
4. If it still isn't fixed, go back to your settings > change to the correct year and return to Passbook and try again.