Can not set Anti Theft as device admin

Avast Mobile Apps Avast Anti-Theft for Android
1

I can not set Anty Theft as Device Admin.
I have a S6 Edge, rooted with 5.1.1
Need Help

2

Same problem on my tablet. I select it in the Device Administrators list, get a pop up, I click ‘Activate’, then the pop up disappears and the program is still unchecked / not selected in the device administrators list.

Avast Mobile with Premium Subscription
Samsung Galaxy Tap Pro 8.4
Rooted Android 4.4.2