Keyboard accelators & user signals

[Kilobug <le-mig_g epita fr>]

I'm trying to add a keyboard accelerator to a signal I've created and I get
the following error message:
Gtk-WARNING **: gtk_accel_group_add(): signal "left_arrow" in the `GtkDrawingArea' class ancestrycannot be 
used as accelerator signal

The code is:
  gtk_object_class_user_signal_new(gtk_type_class (GTK_TYPE_WIDGET),
                                   "left_arrow",
                                   GTK_RUN_LAST | GTK_RUN_ACTION,
                                   gtk_marshal_NONE__POINTER,
                                   GTK_TYPE_NONE, 1,
                                   GTK_TYPE_POINTER);
  gtk_signal_connect(GTK_OBJECT(conf->main), "left_arrow",
                     (GtkSignalFunc) gamearea_left_arrow, conf);
  gtk_widget_add_accelerator(conf->main, "left_arrow", accel_group, 
                             GDK_Left, 0,
                             GTK_ACCEL_VISIBLE);


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 ** Gael Le Mignot, Ing2 EPITA, Coder of The Kilobug Team **
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