WPF datagrid filter doesn't work dosen't work

Greetings,

I'm trying to have a WPF data grid results filtered and I can't get it to work.  The filter event never fires and all the rows remain.

   <DockPanel.Resources>
                                   
                                            
     <CollectionViewSource x:Key="DetailsCollection" 
                           Filter="PriceDetailsFilter" 
                           Source="{Binding Path=PriceChangeDetails, 
                           UpdateSourceTrigger=PropertyChanged}" >
     </CollectionViewSource>
                                           
    </DockPanel.Resources>
                                      
                                            
  <wpf:DataGrid  CanUserSortColumns="True" CanUserAddRows="False" IsReadOnly="False"
      Block.TextAlignment="Left" 
      ItemsSource="{Binding Source={StaticResource DetailsCollection}, 
   UpdateSourceTrigger=PropertyChanged}"> 
    public void PriceDetailsFilter(object sender, FilterEventArgs e)        {            e.Accepted = false; // breakpoint never hits                    }

  Does anyone see what I'm doing wrong?
Thanks,