Before installing it to your phone, you actually need to sign the app. This can be done by downloading appsign.apk file and it has a little bit procedure to do.
First download the SignAPK tool - http://www.mediafire.com/?rw57ftajd6nm81s
Extract them to a directory you will remember. I have put them in C:\SignApk
Now just open cmd and type -
Quote
cd C:\SignApk java -jar signapk.jar certificate.pem key.pk8
your-app.apk your-app-signed.apk
Example -
java -jar signapk.jar certificate.pem key.pk8
D:\nfsshift\dist\nfsshift.apk D:\nfsshift\dist\nfsshift-signed.apk
Your APK is signed and can be installed.
