Well, it looks like you haven't enabled installation of app from unknown source head out to Settings>Security> Under Device Administration, make sure you have ticked the "Unknown Sources". I somewhere get a feel that as you are trying to install .apk file over your device from source other than playstore and settings maybe blocking the app from installing. Do ran a check over it and if you still find that you're unable to install the .apk file then try heading over to the settings>app manager and clear the cache and the data stored by the Google Play App.
— modified on Oct 29, 2014, 10:22:56 AM
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