Gtkmm-documentation, Gtk::TreeStore::move(...). What is an unsorted store by TreeStore?

[Dimitri Holz <d holz innoventis de>]

This is a sector of documentation:

void Gtk::TreeStore::move(const iterator & source, const iterator &
destination)
....
.... Note that this function only works with unsorted stores.


What means with "unsorted stores" ?
(TreeStore is derriven from TreeSortable...)

I need to call this method in my project, but it doesnt work (the row
isn't moved after call). I do not sort the rows and i need the TreeStore
as the model of the TreeView.
How is it possible to do "unsorted store" with TreeStore?


Thanks in advance!