[flexcoders] DataGrid in custom component not updating

[netdeep]

I have a custom component with a DataGrid in it. The dataprovider is an 
actionscript object 
(the variable name for this object is axis) with an ArrayCollection called 
seriesList. When I do 
axis.seriesList.addItem(), the DataGrid updates properly, but when I simply 
assign a new axis 
object (such as for a load) to my component (even for a brand new component) 
with a 
seriesList already defined, it does not update at all. How can I get the 
DataGrid to update 
properly?

<mx:DataGrid id="seriesTable" dataProvider="{axis.seriesList}"  >
        <mx:columns>
                <!-- columns defined here...  -->
         </mx:columns> 
</mx:DataGrid>