title: What does "Failed to initialize App Engine SDK at [path]" mean, and how to fix it?
body: <p>I'm using the the "Google Plugin for Eclipse", and installed both the "Web Toolkit SDK" and the "App Engine Java SDK" with it. Weirdly, the App Engine SDK can't be initialized while the Web Toolkit SDK works fine. Trying to point Eclipse to the root GAE SDK directory will cause the "Failed to initialize App Engine SDK at [path]" error. Downloading the GAE SDK separately will yield the same result.</p>
  
  <p>I'm guessing the error is caused by a version problem?
  Here is the setup:</p>
  
  <ul>
  <li>Eclipse 3.7 Indigo</li>
  <li>Google Plugin for Eclipse 3.7  </li>
  <li>appengine-java-sdk-1.6.4 , appengine-java-sdk-1.6.5 (manual download)</li>
  <li>Java JVM 1.6   </li>
  <li>Mac OSX 10.5, 32bit</li>
  </ul>
  
  <p>Thanks!</p>