then it seems that your phone already has some ngage files installed by default... take a closer look at ''application manager'' and uninstall anything associated with ngage then try again.... also make sure your phone is hacked properly, try to install some other unsigned files (some apps)
I've check the application manager and found nothing associated with n-gage. Also im sure my phone is hacked properly as i was able to install a unsigned helloOX2.