title: Android Studio running Error
body: <p>I tried running an android studio app on an android device and it doesn't seem to be working. The run window said:</p>
  
  <pre><code>04/11 08:29:55: Launching app
  $ adb push /Users/kids/AndroidStudioProjects/Calculator/app/build/outputs/apk/app-debug.apk /data/local/tmp/com.piggyinc.calculator
  com.android.ddmlib.AdbCommandRejectedException: device unauthorized.
  This adb server's $ADB_VENDOR_KEYS is not set
  Try 'adb kill-server' if that seems wrong.
  Otherwise check for a confirmation dialog on your device.
  Error while Installing APK
  </code></pre>
  
  <p>Could anyone help me? By the way it is correct api level. I chose 4.0.3 and this device is like a 5.1</p>