WPF ListView Items Filter - Filter not triggered after refresh Items

Question

I'm trying to add a Filter to my ListView. The filter depends on an input from a TextBox. I'm adding a filter to the ListView and trigger a Refresh if the TextBox Input is changed. My Problem: The Filter Method is only called once.

What I have:

I got a ListView in a XAML file.

<TextBox Grid.Row="0" x:Name="textBoxGroupLayers" FontSize="14" TextChanged="textBoxGroupLayers_TextChanged"/>
<ListView Grid.Row="1" x:Name="listViewGroupLayers" FontSize="14" />

I'm adding Items to the ListView via

listViewGroupLayers.Items.Add(itemToAdd);

I'm adding the Filter:

this.listViewGroupLayers.Items.Filter = UserFilter;

Notice: listViewGroupLayers is a ListView and listViewGroupLayers.Items is an ItemCollection.

My Filter:

       private bool UserFilter(object item)
    {
        if (String.IsNullOrEmpty(this.textBoxGroupLayers.Text))
        {
            return true;
        }
        else
        {
            MyObject myObject = (item as ListViewItem).Tag as MyObject;
            if (myObject == null)
            {
                 return true;
            }
            bool itemShouldBeVisible = myObject.Name.IndexOf(this.textBoxGroupLayers.Text, StringComparison.OrdinalIgnoreCase) >= 0;
            return itemShouldBeVisible;
        }
    }

The Refresh:

        private void textBoxGroupLayers_TextChanged(object sender, TextChangedEventArgs e)
    { 
        this.listViewGroupLayers.Items.Refresh();     
    }

Now happens the following: I setted a Breakpoint in the UserFilter. If I type the first letter in the TextBox, the Breakpoint is gonna be active and the filter is working fine. But if I type the second letter now, the filter isn't called.

If I just do the following, everything works fine:

        private void textBoxGroupLayers_TextChanged(object sender, TextChangedEventArgs e)
    { 
        this.listViewGroupLayers.Items.Filter = UserFilter;     
    }

But this seems pretty dirty to me. My question: Why isn't the filter working after the first time called? I checked the instance of this.listViewGroupLayers.Items and it always has the filter object.