Glib::Dialog signal_key_press_event problem

[Culpian Camilo Martin <camiloculpian gmail com>]

Hi, I'm having a problem, when i connect a dialog to a
signal_key_press_event, the event is not triggered

I Connect:

my_dialog->signal_key_press_event().connect(sigc::mem_fun(*this,
&class_my_dialog::on_key_press_event));

(my_dialog is a pointer to a Gtk::Dialog, i load them with gtkbuilder,
and pass them with GtkBuilder_ref->get_widget("dialog.ui",my_dialog)
inside the class class_my_dialog)

And the funcion 

bool class_my_dialog::on_key_press_event(GdkEventKey *event)

Is never called, Why?