WrapPanel in ItemsPanelTemplate doesn't work when ListBox.GroupStyle is applied.

<ListBox ItemsSource="{Binding Reports}" Margin="10,92,10,10" ScrollViewer.HorizontalScrollBarVisibility="Disabled"  ScrollViewer.VerticalScrollBarVisibility="Disabled">
           <ListBox.GroupStyle>
               <GroupStyle>
                   <GroupStyle.HeaderTemplate>
                       <DataTemplate>
                           <TextBlock Text="{Binding Path=Name}" />
                       </DataTemplate>
                   </GroupStyle.HeaderTemplate>
               </GroupStyle>
           </ListBox.GroupStyle>
           <ListBox.ItemsPanel>
               <ItemsPanelTemplate>
                   <WrapPanel Orientation="Vertical" IsItemsHost="True">
                   </WrapPanel>
               </ItemsPanelTemplate>
           </ListBox.ItemsPanel>
       </ListBox>