Great app  but not very compatible with the new S7 security policies. So it won't probably work very well on any Samsung device with Android 6.0. This is the issue. I use my fingerprint to unlock the phone. If the screen comes on because of this app  next time I want to unlock the phone it says that because of security policies to protect my fingerprint I have to use the PIN number :( Developer  not sure if there's any way to fix this  but if you google it you'll see that it's not only your great app.
April 21 2016