This note from the Android Developer site is what worked for me:
Enable USB debugging on your device. On most devices running Android 3.2 or older, you can find the option under Settings > Applications > Development. On Android 4.0 and newer, it's in Settings > Developer options. Note: On Android 4.2 and newer, Developer options is hidden by default. To make it available, go to Settings > About phone and tap Build number seven times. Return to the previous screen to find Developer options.