Why can't i install apps from other sources?

[AC Question]

I just downloaded an app but i can't install it ...
I dont even have a bluelight effect or something ..
Still can't press the install button

 

[mhinc]

I just downloaded an app but i can't install it ...
I dont even have a bluelight effect or something ..
Still can't press the install button ????????????

If it's an APK your phone is defaulted to warn you about installing from 3rd party sources.
What phone do you have? You would be able to allow 3rd party APKs in your settings