web app sencha touch
<p>i have some problems in this part of code javascript in sencha touch , and i dont know how to resolve that one , </p>

<pre><code>    new Ext.application({
name: 'TouchStart',
launch: function() {

this.viewport = new Ext.Panel({
fullscreen: true,
bodyPadding: 5,
dockedItems: [
{
dock : 'top',
xtype: 'toolbar',
title: 'Touch Start'
},
{
dock : 'top',
xtype: 'toolbar',
items: [
{
text: 'Hello Button'
}
]
}
],

html: 'Hello Panel'
});
}
});
</code></pre>

<p>the console show :</p>

<pre><code>this.viewport = new Ext.Panel({
</code></pre>

<blockquote>
  <p>Uncaught TypeError: undefined is not a function</p>
</blockquote>
