APK file "app not installed" error message EVERY TIME

[Moltres_rider]

I have a file manager app that installed just fine on my Droid Razr but REFUSES to install on the Samsung Galaxy s4!!! I have changed the settings to allow installations from unknown sources and other APK's installed just fine but NOT this one!!! it ALWAYS gives an error "app not installed" with NO OTHER INFORMATION attached to it whatsoever!!! just a "app not installed" was wondering if you can help me fix it

 

[B. Diddy]

I wonder if it might be an issue with Knox. Also, not all apps are compatible with all devices or Android versions. I assume your S4 has a higher Android version than the Razr, so that might be part of it.

Are you able to install the actual app from the Play Store? Does it even come up as compatible with your S4? If not, then compatibility is likely the issue.