Then I got the dreaded message 'App not Installed' I then opened google drive and clicked on my App1.apk and chose to install it (need to ensure you have allowed installation of apks in settings). After disconnecting my nexus from the usb, I went to the settings/apps and uninstalled my app (App1).
I then created a signed apk and uploaded to my Google Drive. For me the situation was this: I had deployed to my nexus 7 (actual device) from within the Android Studio (v1.3.2).
Clearly there are many causes of this problem.
