run 'adb devices' in command line client, if your phone has been connected adb, it will show up here but more importantly it will display the correct device name you need to reference in your capabilities.
From here I would compare and see if they match, if they dont use what is found for the device name in your capabilities.
note: if you have not configured the 'adb' environment path, cd to android-sdk/platform-tools/, then run it.