pylab without X11

[Willem-Jan Vriend]

I want to use pylab (matplotlib) on a machine without X11. I'm trying to 
generate onthefly graphics for an apache2 web service, so they do not 
have to be displayed on this machine !

When i do
    pylab.figure()
I get the error
    TclError: couldn't connect to display ":0.0"

I tried setting the DISPLAY environment variable to "", ":0.0" but I got 
the same error message.

Any help is very much appreciated.