Problem with graph tool visualization

I tried to plot a graph or run the animation example. But, I always get this
error
cairo_surface_set_device_scale.
Importing graph_tool,gi and pygtk is not a problem in python. Has anyone had
this problem before?
I am using ubuntu 14.04 and python 2.7* (anaconda distribution).

Please provide a self-contained example that reproduces the problem and
the _full_ error message.

Best,
Tiago