where is error? (Glib::spawn_async)

[Paul Pogonyshev <pogonyshev gmx net>]

Hi.

Where is error in this code fragment?

      std::vector <std::string>  yelp_arguments;

      yelp_arguments.push_back ("yelp");
      yelp_arguments.push_back ("ghelp:///usr/share/gnome/help/gedit/C/gedit.xml");

      try
	{
	  Glib::spawn_async (".", yelp_arguments, std::vector <std::string> (),
			     Glib::SPAWN_SEARCH_PATH);
	  return;
	}
      catch (Glib::Error& exception)
	{
	  g_print ("%s...\n", exception.what ().c_str ());
	}

I get this in terminal:

    (yelp:14036): Gtk-WARNING **: cannot open display:

and Yelp window is never shown.

Paul