gtk_combo_box_set_model fails to set model...

[Setzer- <setzer sm-soft org>]

I'm trying to use the new gtk_combo w/ models, however, after I set the
model I had created to a combo box,
using gtk_combo_box_get_model returns NULL.

the model is created as follow :
GtkTreeModel *symboles_list;
   symboles_list = GTK_TREE_MODEL (gtk_list_store_new(3,
                   G_TYPE_STRING,
                    G_TYPE_POINTER,
                    G_TYPE_BOOLEAN));
// At this point, symboles_list is succesfully created (i.e. != NULL)
/* ... */

// fill it with some data (variables were filled earlier in the code)
gtk_tree_store_append(GTK_TREE_STORE(symboles_list), &iter, NULL);
gtk_tree_store_set(GTK_TREE_STORE(symboles_list), &iter,
                       0, key,         // Col 0 set to key
                       1, preclist,    // Col 1 set to list pointer
                         2, IsTerminal, -1);    // Col 2 set to IsTerminal

// Attach the model to the combo box
   gtk_combo_box_set_model(GTK_COMBO_BOX (symboles),
GTK_TREE_MODEL(symboles_list));

// Verify
   model = gtk_combo_box_get_model(GTK_COMBO_BOX(symboles));
//model == NULL. : (

earlier in the code,
GtkWidget *symboles;
GtkCellRenderer *renderer;

symboles = gtk_combo_new();

       renderer = gtk_cell_renderer_text_new ();
       gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (symboles),
renderer, FALSE);
       gtk_cell_layout_add_attribute (GTK_CELL_LAYOUT (symboles),
renderer, "text", 0);

// Then the function to create the model, fill it and attach it is called.

This code follows that of
http://mail.gnome.org/archives/gtk-list/2004-June/msg00253.html,
which was probably mentioning the same problem.
BTW, I have GTK+ 2.4.3 win32.