firefox.apk does not install on a device after the was extracted. what to do?

hi,

I installed firefox from google play on device "1".
I then used es file explorer (and ASTRO) to back up the application.
The resulting apk was saved on a sd card and I used said card on device "2" which has no google play on it.

device 2 trying to install but after a few seconds a message appears which says "App not installed".

What is going on and what can I do?

Thank you!