title: Error #2109 half the time
body: <p>I'm making a platform game in AS3. </p>
  
  <p>Everything is running fine except sometimes (not each time I run the game), I've got this error : </p>
  
  <pre><code>ArgumentError: Error #2109: Frame label null not found in scene null.
      at flash.display::MovieClip/gotoAndStop()
      at PlatformGame/moveCharacter()[C:\...\PlatformGame.as:581]
      at PlatformGame/moveEnemies()[C:\...\PlatformGame.as:360]
      at PlatformGame/gameLoop()[C:\...\PlatformGame.as:348]
  </code></pre>
  
  <p>I don't understand AT ALL why it happens randomly..</p>
  
  <p>Do you know what could be the problem ?</p>
  
  <p>Here's the lines in the error :</p>
  
  <p>line 581 : </p>
  
  <pre><code>char.mc.gotoAndStop(char.walkAnimation[Math.floor(char.animstep)]);
  </code></pre>
  
  <p>line 360 :</p>
  
  <pre><code>moveCharacter(enemies[i],timeDiff);
  </code></pre>
  
  <p>line 348 : </p>
  
  <pre><code>moveEnemies(timeDiff);
  </code></pre>
  
  <p>Thank you for your help, </p>