Android 5 disable install button of apk files on nexus 4 After updating my nexus 4 to new android 5 (lollipop) when i open an apk file, the install button not working!!
Also i checked unknown source in my device settings.  

What the problem? please help :(
I have used lux lite application, this application set display brighness for reading in night mode. my problem solved when i unistall this app.