add list to gtk_tree_view in C - gtk

Question

folks,
im gonna tryin to make a little function which has something todo with the Gtk_tree_view that i've made,
the error response such as like this :
(main:8026): Gtk-CRITICAL **: IA__gtk_tree_view_get_model: assertion `GTK_IS_TREE_VIEW (tree_view)' failed
(main:8026): Gtk-CRITICAL **: IA__gtk_list_store_append: assertion `GTK_IS_LIST_STORE (list_store)' failed
(main:8026): Gtk-CRITICAL **: IA__gtk_list_store_set_valist: assertion `GTK_IS_LIST_STORE (list_store)' failed
^C
and the source, here you go :
void addlist(bahan *unit, const gchar *str)
{
GtkListStore *store;
GtkTreeIter iter; // penyambung store_append and store_set
store = GTK_LIST_STORE(gtk_tree_view_get_model(GTK_TREE_VIEW(unit->treeview_aktifitas)));
gtk_list_store_append(store, &iter); // need unary &, coz iter aint define like a pointer
gtk_list_store_set(store, &iter, 1, str, -1);
}
as you've figured , the structure of 'unit' was supposed like this :
typedef struct
{
GtkWidget *window;
GtkWidget *notebook;
GtkWidget *start;
GtkWidget *verbose;
GtkWidget *settings;
GtkWidget *about;
GtkWidget *statusbar;
GtkWidget *treeview_aktifitas;
guint statusbar_id;
} bahan;
and connected by this :
unit->treeview_aktifitas = GTK_WIDGET(gtk_builder_get_object(main,"treeview1"));
in the real case, im using 'glade 3', and have two columns on glade file, how to set on gtk_list_store_set ?
very appreciate any further help :)

Answer 1

well, i've found the fault now
gtk_list_store_set(store, &iter, 1, str, -1);
just because my columns are two ,thus i need to
gtk_list_store_set(store, &iter, 0,"aku", 1, "tes", -1);
which 0 represent first column and 1 represent next column, and so on -_-'