Why I cannot put filters in a group container?

programming flash
1

I am trying to design a custom group container. This is my code below. I have a Group openning tag and a GlowFilter inside the declarations. When I run the code, it gives me error

ArgumentError: Error #2005: Parameter 0 is of the incorrect type. Should be type Filter.

I have no idea what went wrong. The code compiles fine, but not able to run. The workaround is change the Group to BorderContainer or remove the filters, but I just don’t see why Group has a problem with it. Can anyone help?
I have attached my simplest project file.

Thanks.

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
           xmlns:s="library://ns.adobe.com/flex/spark" 
           xmlns:mx="library://ns.adobe.com/flex/mx">
     
     <fx:Script>
          <![CDATA[
               import spark.core.MaskType;
          ]]>
     </fx:Script>
     
     <fx:Declarations>
          <!-- Place non-visual elements (e.g., services, value objects) here -->
          <s:GlowFilter id="gF" blurX="12" blurY="12" color="#000000"/>
     </fx:Declarations>
     
     <s:Label text="test" filters="{[gF]}"/>
</s:Group>