With the introduction of iOS 9, Apple slightly changed their security guidelines. This makes it necessary for you to mark PressMatrix as a trusted developer in the settings of your device. 

1. When you first open the Preview App you’ll see a notification that the developer of the app isn’t trusted on your device. You can dismiss this message but you can’t open the app. 
   
   
2. Now switch to „Settings“ > „General“ > „Device Management“. You should see the PressMatrix profile . 
   
   
   
3. Tap the profile to establish trust for PressMatrix.
   
   
   
   
4. You’re then prompted to confirm your choice. Once you trust our PressMatrix profile, you can manually install other apps us and open them immediately.