APK can download to phone, but cannot open on device

I have created and built and app successfully. I have put it on my device and emulator.
Now my app cannot open on any device, im not sure what the problem is. I have provided my player settings in the picture below. When i try to open the app is says,
"Unfortunately the app has stopped".
My phone and emulator both have a higher version, than the minimum API level which is Android 4.1.

I have tried everything, can someone please help?