AttributeError, why?
<p>I'm writing a program that solves a tetravex and I encountered this error:</p>

<pre><code>AttributeError: 'list' object has no attribute 'PlacementList'.
</code></pre>

<p>I tried everything I know but don't know why I'm getting that error. Could you please tell me what I did wrong?</p>

<p>This is a pastebin link to my code: <a href="http://pastebin.com/d1WdbCUu" rel="nofollow">http://pastebin.com/d1WdbCUu</a></p>
