[flexcoders] Changing DataProvider on HorizontalList component

[Amy]

Hi, all;

I have an XMLListCollection I am using as the dataprovider for a 
HorizontalList.  I am not using databinding, so I am setting the 
dataProvider in AS.  When I add an item and refresh the 
XMLListCollection, I expect to see the additional ItemRenderer on the 
screen.  I can see that the XMLListCollection contains the new item, 
and  I can see that code executes inside the existing ItemRenderers 
when I refresh the collection, but the last loop never happend for 
the new data item.

This is my function to add a new item:

public function addSolution():void{
   var s:XML=
      <solution id="0">
         <column num="1">
         </column>
         <column num="2">
         </column>
         <column num="3">
         </column>
         <column num="4">
         </column>
   </solution>;
   solutionsXMLListCollection.addItem(s)
   allSolutions.invalidateList();
   solutionsXMLListCollection.refresh();
   trace('addSolution');
}

What am I missing?

Thanks;

Amy