title: "Ext is not defined" issue in ExtJS 4
body: <p>I came across a "Ext is not defined" issue in ExtJS 4.
  I am actually testing the example <a href="http://docs.sencha.com/ext-js/4-1/#!/api/Ext.data.reader.Reader" rel="nofollow noreferrer">here</a> to starting learning ExtJS 4. </p>
  
  <p>I have my example script file included: </p>
  
  <pre><code>&lt;script type="text/javascript" src="orderRead.js"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" src="order.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>as well as these ExtJS script files: </p>
  
  <pre><code>&lt;script type="text/javascript" src="extjs/ext-all.js"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" src="extjs/ext-all-debug.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>but the problem is still there. Attached is the error message from Firebug: 
  <img src="https://i.stack.imgur.com/ZSi7C.png" alt="enter image description here"></p>