Deriving Widget Class, compile error

[Damianos Mylonakis <danmylonakis gmail com>]

Hello, i am experiencing a problem when trying to compile the example at
http://library.gnome.org/devel/gtkmm-tutorial/unstable/sec-builder-using-derived-widgets.html.en

I compile with :
g++ `pkg-config gtkmm-2.4 --cflags --libs` main.cc

and i get this error :
/tmp/ccm1AzsY.o: In function `void 
Gtk::Builder::get_widget_derived<DerivedDialog>(Glib::ustring const&, 
DerivedDialog*&)':
main.cc:(.text._ZN3Gtk7Builder18get_widget_derivedI13DerivedDialogEEvRKN4Glib7ustringERPT_[void 
Gtk::Builder::get_widget_derived<DerivedDialog>(Glib::ustring const&, 
DerivedDialog*&)]+0x6e): undefined reference to `typeinfo for DerivedDialog'
main.cc:(.text._ZN3Gtk7Builder18get_widget_derivedI13DerivedDialogEEvRKN4Glib7ustringERPT_[void 
Gtk::Builder::get_widget_derived<DerivedDialog>(Glib::ustring const&, 
DerivedDialog*&)]+0x118): undefined reference to 
`DerivedDialog::DerivedDialog(_GtkDialog*, Glib::RefPtr<Gtk::Builder> 
const&)'
collect2: ld returned 1 exit status

I guess it is not a problem with the sources, but with the compilation?
Any idea?

Thank you,
Damianos.