g_object_set_data()

[jls <jls free fr>]

Hi all ;),
         I try to set a glist to a name with the function
         g_object_set_data as follow :
          g_object_set_data(G_OBJECT(DirList),"dirlist",pWindow);
                when I try to get this object with the g_object_get_data
                function, GTK returns :
                 GLib-GObject-WARNING **: invalid uninstantiatable type
                 `<unknown>' in cast to `GtkCList'
                Gtk-CRITICAL **: file gtkclist.c: line
                2673 (gtk_clist_append): assertion `GTK_IS_CLIST (clist)' failed 
                
                                                                                                              
   
          And if I don't cast the object with G_OBJECT a warning is
                returned during the compilation.
                Who can I deal with those functions ? 

                Sincerely

                Jerome