ActionScript 3.0 :: Removing The Selected Items From A List?

I have a Listbox whith a ArrayCollection as datasource. I'm trying to remove the selected items from the ArrayCollection to update the list.Here is how I coded the remove function:

for each (var item:Item in theList.selectedItems)
{
theArrayCollection.removeItemAt(theArrayCollection .getItemIndex(item));
}

This works fine as long as the ArrayCollection is not sorted. When I apply a sort I get a RangeError from ListCollectionView.removeItemAt.