title: AChartEngine crash on release
body: <p>Great library, works well in debug.</p>
  
  <p>However, after I exported a signed application package, it crashes every time I try to fire up a chart. Just, puff!!!</p>
  
  <p>I'm using sdk 19 and targeting 16 min.</p>
  
  <p>Does AChartEngine have any special ProGuard settings?</p>
  
  <p>Any suggestions?</p>
  
  <p>Here is part of the logcat (thanks to keshav):</p>
  
  <pre><code>FATAL EXCEPTION: main
  java.lang.NullPointerException
  at android.view.GLES20Canvas.drawBitmap(GLES20Canvas.java:739)
  at android.view.GLES20RecordingCanvas.drawBitmap(GLES20RecordingCanvas.java:91)
  at a.a.b.onDraw(Unknown Source)
  at android.view.View.draw(View.java:13944)
  at android.view.View.getDisplayList(View.java:12838)
  </code></pre>