Try doing the following:
1. Restart the app.
2. Restart your phone/tablet.
3. Make sure that you have installed iOS 7 or higher or Android 4.0 or higher on your phone/tablet.
If none of the above work, you can send an e-mail to our support team at firstname.lastname@example.org or simply live chat with us right away via the blue chat icon in the lower right corner here on the website or in the Napp® CMS.