tree widget not displaying

[Chris De Maeyer <chrisdm pandora be>]

Having difficulty with a tree widget, seems to be processed but doesn`t
display anything in my gui:

	vboxa0 = gtk_vbox_new (FALSE, 0);
	
	framea1 = gtk_frame_new (" Airport ");
	gtk_container_set_border_width (GTK_CONTAINER (framea1), 10);
	
	gtk_container_add (GTK_CONTAINER (vboxa0),framea1);
	labela = gtk_label_new (" Airport ");
	
	store = gtk_tree_store_new (N_COLUMNS,
			G_TYPE_STRING,
			G_TYPE_STRING);
	FillAirports(store);
	tree = gtk_tree_view_new_with_model (GTK_TREE_MODEL (store));
	g_object_unref (G_OBJECT (store));
	renderer = gtk_cell_renderer_text_new ();
	g_object_set (G_OBJECT (renderer),
		"foreground", "red",
		NULL);
	column = gtk_tree_view_column_new_with_attributes ("ID", renderer,
			"text", ID_COLUMN,NULL);
	gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);
	renderer = gtk_cell_renderer_text_new ();
	column = gtk_tree_view_column_new_with_attributes ("Location",
renderer,
			"text", NAME_COLUMN,NULL);
	gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);
	
	gtk_widget_show (tree);
	gtk_widget_show (renderer);
	gtk_widget_set_size_request(vboxa0,640,100);
	gtk_widget_show (vboxa0);
	gtk_widget_show (framea1);

and the tree composer function:

int fgk_ReadAirports(char *flyfile,GtkTreeStore *st)
{
	FILE *tmp;
	char str[256];
	char word2[32];
	int start,einde;
	
	GString *tok;
	
	if((tmp=fopen(flyfile,"r"))!=NULL) {
		while(!feof(tmp)) {
			fgets(str,sizeof(str)-1,tmp);
			
			start = getDelimPos(str,' ',1);
			einde = getDelimPos(str,' ',2);
			memset(word2,0,32);
			memcpy(word2,str+start,einde-start);
			
			tok = g_string_new(word2);
			/*combo_airports_list=g_list_append (combo_airports_list,
tok->str);*/
			GtkTreeIter iter1;  /* Parent iter */
			
			gtk_tree_store_append (st, &iter1, NULL);  /* Acquire a top-level
iterator */
			gtk_tree_store_set (st, &iter1,
				ID_COLUMN, tok->str,
				NAME_COLUMN, "Donald E. Knuth",
				-1);
		}
		fclose(tmp);
	} else {
		return(-1);
	}	
	return(0);	
}	

Any ideas or remarks why this widget is not working?