Hi there

Just installed graph-tool for the first time & get this error. What does it mean? How can i fix? I'm on Ubuntu Server 12.04

Much appreciated

>>> from graph_tool.all import * 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/graph_tool/all.py", line 31, in <module>
    from graph_tool.draw import *
  File "/usr/lib/python2.7/dist-packages/graph_tool/draw/__init__.py", line 589, in <module>
    from cairo_draw import graph_draw, GraphWidget, GraphWindow, \
  File "/usr/lib/python2.7/dist-packages/graph_tool/draw/cairo_draw.py", line 59, in <module>
    from gi.repository import Gtk, Gdk, GdkPixbuf
  File "/usr/lib/python2.7/dist-packages/gi/importer.py", line 76, in load_module
  File "/usr/lib/python2.7/dist-packages/gi/module.py", line 224, in _load
    overrides_modules = __import__('gi.overrides', fromlist=[self._namespace])
  File "/usr/lib/python2.7/dist-packages/gi/overrides/Gtk.py", line 1517, in <module>
    raise RuntimeError("Gtk couldn't be initialized")
RuntimeError: Gtk couldn't be initialized