Impossible to create graph

[Simon Schmidig]

Binary package hint: openerp-server

Startup message:
Environment Information :
System : Linux-2.6.31-15-generic-i686-with-Ubuntu-9.10-karmic
OS Name : posix
Distributor ID: Ubuntu
Description: Ubuntu 9.10
Release: 9.10
Codename: karmic
Operating System Release : 2.6.31-15-generic
Operating System Version : #49-Ubuntu SMP Fri Nov 6 09:52:03 UTC 2009
Operating System Architecture : 32bit
Operating System Locale : fr_CH.UTF8
Python Version : 2.6.4
OpenERP-Client Version : 5.0.3
Last revision No. & ID :Bazaar Package not Found !Traceback (most recent call last):
  File "/usr/lib/openerp-client/widget/view/graph_gtk/parser.py", line 57, in parse
    import graph
  File "/usr/lib/openerp-client/widget/view/graph_gtk/graph.py", line 43, in <module>
    import tinygraph
  File "/usr/lib/openerp-client/tinygraph/__init__.py", line 22, in <module>
    import matplotlib
ImportError: No module named matplotlib