downloading kingroot I have tried to download king root to root my device. Have downloaded it but can't install it onto my phone, this has happened with a root tool as well.these have been downloaded from the internet and unknown sources has been to ticked. I used to be able to download stuff like this before now I cant. Can this be fixed?
It's been a year, so this isn't necessarily for op, but for anyone with the problem. I just had this problem and fixed it. 

Even with unknown sources ticked, I was still getting a warning message. I just pressed okay without looking, and the app wouldn't install.

Instead, when you get that warning just press more info, then press install anyway. It's smaller text and a different color--easy to miss.

That should do it.