Hi,
when you build for Android, there's 2 stages. Stage 1 does a release build in the distribute directory. You can code sign that later.
Stage 2 does a debug build and installs it. If it fails, your device is not connected or the drivers are not installed.
Here's a fix that helped me:
http://rootzwiki.com/topic/6859-how-tofixing-usb-problems-with-adb/ (http://rootzwiki.com/topic/6859-how-tofixing-usb-problems-with-adb/)
Basically you browse all devices in device-manager start start with "USB---" and select "reinstall drivers / autmoatically find best driver".
Make sure your android device has USB-debugging active (settings/apps/debugging).