I recently purchased a Nexus 10. I'm trying to install the Amazon App Store which is not in the Play Store, but instead is a file that I can download from Amazon. I've selected "Unknown Sources" option in the security settings and when I go to install the Amazon App Store App it gives me the option to install it, but it won't actually let me select the install button. I'm not rooted at all and running a totally stock version of Android 4.2.2 on my Nexus 10. Any ideas as to how I can get this app to install with out rooting my tablet?