App cannot be started (after install or update)

[Radim]

Because of one small WP8.1 issue (RPC failure) you may encounter a problem the application can not be started after the first install or update.
To fix that please try:
- open any song (play and stop) in build-in default Music application, then close it
- now try run MusicMan again

Second option is to restart your device.
Hope that helped!