Unregistered object at path '/org/freedesktop/NetworkManager/Devices/0'

[Bluehazzard <bluehazzard2 gmail com>]

Hi all,
I'm completely new in d-bus programming. I use the glib-dbus API, to 
communicate with the Network Manager.
The first thing i want to realize is a program, what lists me the 
available devices.
Sou i thought that this code should work:

NetworkManagerProxy = dbus_g_proxy_new_for_name_owner( bus,
                                                                        
                                        NM_DBUS_SERVICE,
                                                                        
                                        NM_DBUS_PATH ,
                                                                        
                                        NM_DBUS_INTERFACE ,
&error);


char **name_list;
char **name_list_ptr;

if (!dbus_g_proxy_call (NetworkManagerProxy, "GetDevices", &error, 
G_TYPE_INVALID,
                                        DBUS_TYPE_G_OBJECT_ARRAY, 
&name_list, G_TYPE_INVALID))
{
    /*error*/
    if(error->domain == DBUS_GERROR)
    {
        cout << error->message << endl;
    }
    g_error_free (error);
}
else
{
    for (name_list_ptr = name_list; *name_list_ptr; name_list_ptr++)
    {
        //List of devices
    }
}

But i get always the errormessage "Unregistered object at path 
'/org/freedesktop/NetworkManager/Devices/0' "
what does this mean?

thank you for the answers, and sry for my very poor English.