I\'m attempting to transition from Eclipse to Android Studio today. I generated the Gradle build files in Eclipse and imported into Android Studio. I changed my preferences
This is to do with the RSA security authentication that happens between your PC and mobile. When you connect your mobile device with USB debugging enabled, you must be getting a popup to authorize the computer to use USB debugging on your device. Just check "Always allow" and things should work smoothly.
Actual problem is when you connect your device to your PC the first time after enabling the USB debugging, the popup for RSA authentication just disappears after a while. So all you have to do is, disconnect and reconnect the mobile device and set the authorization on popup.