title: Can't add library to my android project
body: <p>I'm creating a new app and I want to use some libraries like this:
  <a href="https://github.com/JakeWharton/Android-ViewPagerIndicator" rel="noreferrer">https://github.com/JakeWharton/Android-ViewPagerIndicator</a></p>
  
  <p>I had downloaded this library, added it to my workspace using New Android Project -> Create from existig source.
  Went to properties > android, and checked <code>Is Library</code>.
  Then I went to properties > android in my app project, and clicked add on the Libraries section, and chose the library, and It show me the library with a green V near it.
  I've clicked ok, but couldn't use the library so I've opened the properties > android again, and there was a red cross near the library, and '?' under the "Project" column.</p>
  
  <p>I can't understand why it's happening! It's really annoying, happened to me when I tried to add facebook API to my app, and I just gave up and copied the source to my project.</p>
  
  <p>Thanks, Elad!</p>