pychart unicode error

Operating System Architecture : 64bit
Operating System Locale : en_US.UTF8
Python Version : 2.5.2
OpenERP-Server Version : 5.0.6
Last revision No. & ID : 1872 <email address hidden>

Exception: 'ascii' codec can't encode character u'\xfc' in position 8: ordinal not in range(128)
Traceback (most recent call last):
  File "/home/terp/OpenERP/branch/server/5.0/bin/service/web_services.py", line 687, in go
    (result, format) = obj.create(cr, uid, ids, datas, context)
  File "/home/terp/OpenERP/branch/server/5.0/bin/addons/stock/report/product_stock.py", line 112, in create
    gt.draw()
  File "/home/terp/OpenERP/branch/server/5.0/bin/addons/stock/report/stock_graph.py", line 99, in draw
    ar.draw(self._canvas)
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/area.py", line 245, in draw
    self.legend.draw(self, legends, can)
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/legend.py", line 144, in draw
    max_label_width[col] = max(l.label_width(), max_label_width[col])
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/legend.py", line 44, in label_width
    return font.text_width(" " + self.label)
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/font.py", line 426, in text_width
    (xmin, xmax, d1, d2) = get_dimension(text)
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/font.py", line 394, in get_dimension
    (xmax, ymax, halign, valign, angle) = unaligned_get_dimension(text)
  File "/home/terp/OpenERP/branch/server/5.0/bin/pychart/font.py", line 360, in unaligned_get_dimension
    for line in str(text).split("\n"):
UnicodeEncodeError: 'ascii' codec can't encode character u'\xfc' in position 8: ordinal not in range(128)