I've been trying out Flash Builder for the first time and I can't seem to get it working...

First off I have these bits of very basic code:

The MXML:

```
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" xmlns:ns1="*">
    <fx:Script>
        <![CDATA[
            public function initApp():void 
            {
                var spiro:Spiro = new Spiro();

            }
        ]]>
    </fx:Script>
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>

</s:Application>

```

And also the AS3:

```
package
{
    import flash.display.Sprite;

    public class Spiro extends Sprite
    {
        public function Spiro()
        {
            var mainRect:Sprite = new Sprite();

            mainRect.graphics.beginFill(0x0000FF);

            mainRect.graphics.drawRect(0, 0, 100, 100);
            mainRect.graphics.endFill();
            addChild(mainRect);

        }
    }
}

```

This code does nothing. But when I add a Flex component using the WYSIWYG Design view, the component IS visible.

Another key problem: Flash Builder cannot connect to the debugger, even though I've installed it twice now. Can anyone help me here? I've made sure my firewall is off, but could this be causing problems?

Many thanks.