'Vector' declaration must be contained within the <Declarations> tag

Steps to reproduce:
1. Download Flex Builder 4 (SDK 4.0.0 8708)
2. Create a Flex Project
3 Copy paste example from http://opensource.adobe.com/wiki/display/flexsdk/MXML+Vector+Support

<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/halo">
<fx:Vector id="myVector" type="String" fixed="true">
<fx:String>hi</fx:String>
<fx:String>bye</fx:String>
</fx:Vector>
</s:Application>

Actual Results:

Description Resource Path Location Type
'Vector' declaration must be contained within the <Declarations> tag, since it is not assignable to the default property's type 'Array' or element type 'mx.core.IVisualElement'. FlexTest.mxml FlexTest/src line 6 Flex Problem

<?xml version="1.0" ?>

• <flex-sdk-description>
  <name>Flex 4.0</name>
  <version>4.0.0</version>
  <build>8708</build>
  </flex-sdk-description>