title: The output jar is empty. Did you specify the proper '-keep' options?
body: <p>I am trying to build a release APK file from ant and this is what i m getting in my console</p>
  
  <pre><code>D:\AndroidSDK\android-sdk_r18-windows\android-sdk-windows\tools\ant\build.xml:595: The following error occurred while executing this line:D:\AndroidSDK\android-sdk_r18windows\android-sdk-windows\tools\ant\build.xml:864: The output jar is empty. Did you specify the proper '-keep' options?
  </code></pre>
  
  <p>What is this error and how can i resolve it..M using the latest SDK(API-17) with Revision 21.1
  All java_home,Ant_home are set</p>