hiding progressbar in a Gtk2::TreeViewColumn

[anguila <anguila gmail com>]

I have this treeview:
| + Name |pixbuf| ProgressBar|...
| ++ Name_2 |pixbuf| Progressbar|..
|+++ Name_3|pixbuf| Progressbar|..

So my question is, how can I hide the Name_3 Progressbar so achieve this tree:

| + Name |pixbuf| ProgressBar|...|others
| ++ Name_2 |pixbuf| Progressbar|...|others
|+++ Name_3|pixbuf||...others|

code of the model:
...
    my $tc_pbar= Gtk2::TreeViewColumn->new();
    my $pbar = Gtk2::CellRendererProgress->new();
    $tc_pbar->pack_start($pbar,1);
    $tc_pbar->set_attributes($pbar, 'value' => COL_PBAR);
    $tc_pbar->set_sizing ('fixed');
    $tc_pbar->set_fixed_width (150);
...

When i set the values in the rows have the progressbar in the COL_PBAR, but i want that the child of Name_2, Name_3, have no progressbar in the COL_PBAR Column, i tried to put nothing in the field of the COL_PBAR, but still exist in the treeview.
model, when I 
 
 my $Name= $tree_store->append($undef);
 $tree_store->set($Name,COL_FILENAME,"Name",COL_PBAR,0);
 my $Name_2= $tree_store->append($Name);
 $tree_store->set($Name_2,COL_FILENAME,"Name_2",COL_PBAR,0);
 my $Name_3= $tree_store->append($Name_2);
 $tree_store->set($Name_3,COL_FILENAME,"Name_3");


Any idea how to hide this progressbar?