Can't use XML namespaces in datagrid?

Question

I'm using Flex 3 beta 2. When try to bind a datagrid column
to an XML element with a namespace, it doesn't display any value.
if I try the same XML without a namepace, it works fine. For
example, in the simple code below, binding a column with a
no-namespace XML document as :
<mx:DataGridColumn headerText="First"
dataField="firstname"/>
work fine but for the XML case with namespace:
<mx:DataGridColumn headerText="First"
dataField="ex::firstname"/>
does not display the value.
The "ex" namespace is declared earlier in the code and I have
no problem accessing the values with other controls like text or
list box. I actually reported this as a bug but was wondering is
anyone has a work around or a similar cse that is working.
many thanks
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="absolute" width="600" height="244">
<mx:Script>
<![CDATA[
import flash.events.*;
import flash.net.URLLoader;
import flash.net.URLRequest;
public var ex:Namespace = new Namespace("
http://www.example.org/dummy");
[Bindable]
public var testXML:XML =
<root>
<person id="1" initials="JD">
<firstname>John</firstname>
<lastname>Doe</lastname>
</person>
<person id="2" initials="AB">
<firstname>Andy</firstname>
<lastname>Baldwin</lastname>
</person>
<person id="3" initials="CD">
<firstname>Charles</firstname>
<lastname>Darwin</lastname>
</person>
</root>
[Bindable]
public var testXMLNS:XML =
<root xmlns="
http://www.example.org/dummy">
<person id="1" initials="JD">
<firstname>John</firstname>
<lastname>Doe</lastname>
</person>
<person id="2" initials="AB">
<firstname>Andy</firstname>
<lastname>Baldwin</lastname>
</person>
<person id="3" initials="CD">
<firstname>Charles</firstname>
<lastname>Darwin</lastname>
</person>
</root>
]]>
</mx:Script>
<!-- Without a namespace, the column correctly display
the element values -->
<mx:DataGrid x="10" y="10" width="580" height="106"
dataProvider="{testXML.person}">
<mx:columns>
<mx:DataGridColumn headerText="ID" dataField="@id"/>
<mx:DataGridColumn headerText="First"
dataField="firstname"/>
<mx:DataGridColumn headerText="Last"
dataField="lastname"/>
</mx:columns>
</mx:DataGrid>
<!-- With a namespace, the column do not display the
element values -->
<mx:DataGrid x="10" y="124" width="580" height="106"
dataProvider="{testXMLNS.ex::person}">
<mx:columns>
<mx:DataGridColumn headerText="ID" dataField="@id"/>
<mx:DataGridColumn headerText="First"
dataField="ex::firstname"/>
<mx:DataGridColumn headerText="Last"
dataField="ex::lastname"/>
</mx:columns>
</mx:DataGrid>
</mx:Application>

Answer 1

The strange thing is that we have datadrids all over this app that are formatted exactly the same way and this behavior never happens:
Here's another example:
<code>
<mx:DataGrid
                id="contactDataGrid"
                change="onItemSelected()"
                styleName="patientlist"
                width="50%"
                height="100%"
                editable="false"
                draggableColumns="false"
                resizableColumns="false" >
                <mx:columns>
                    <mx:DataGridColumn headerText="Name" dataField="FirstName" />
                    <mx:DataGridColumn headerText="Relationship" dataField="RelationshipToPatientTypeId"/>
                </mx:columns>
            </mx:DataGrid>
</code>