SCF warnings

I get many SCF warnings, when I shut down my application. The text:

SCF WARNING: 1 unreleased instances of class crystalspace.console.input.standard!
SCF WARNING: 1 unreleased instances of class crystalspace.console.output.standard!
SCF WARNING: 1 unreleased instances of class crystalspace.font.server.default!

etc.

I load this plugins with this function:

bool luaConsole::Initialize(iObjectRegistry* obj_reg)
{
   object_reg = obj_reg;

   conout = csQueryRegistryOrLoad<iConsoleOutput> (object_reg,
   "crystalspace.console.output.standard");
if (!conout)
{
csReport (object_reg,
        CS_REPORTER_SEVERITY_ERROR, "lua.console",
      "Can't load the output console!");
return false;
}
conin = csQueryRegistryOrLoad<iConsoleInput> (object_reg,
   "crystalspace.console.input.standard");
if (!conin)
{
csReport (object_reg,
        CS_REPORTER_SEVERITY_ERROR, "lua.console",
      "Can't load the input console!");
return false;
}

conin->Bind (conout);
conin->SetPrompt ("lua:");
ExecCallback* cb = new ExecCallback ();
conin->SetExecuteCallback (cb);
if(!cb->InitLua(object_reg)) return false;

cb->DecRef ();
conout->SetVisible (false);

return true;
}

The exit code is canonical:

csRef<iEventQueue> q =
CS_QUERY_REGISTRY(GetObjectRegistry(), iEventQueue);
if (q.IsValid()) q->GetEventOutlet()->Broadcast(csevQuit(GetObjectRegistry()));

Why I get this wranings?
How can I avoid this?

Thx for any reply!