Dexter won't open in localized versions of Ubuntu

When I'm trying to open from Turkish Ubuntu, the program crashes and it won't open the interface. But when i open from an English Ubuntu there is no problem at all!

Here is the terminal output:

echza@hal:~$ dexter
Traceback (most recent call last):
  File "/usr/bin/dexter", line 33, in <module>
    from dexter.app import DexterApp
  File "/usr/lib/pymodules/python2.6/dexter/app.py", line 27, in <module>
    from dexter.frontend.dialogs.new_contact import NewContactDialog
  File "/usr/lib/pymodules/python2.6/dexter/frontend/dialogs/new_contact.py", line 26, in <module>
    from dexter.frontend.widgets.entries import HintedEntry
  File "/usr/lib/pymodules/python2.6/dexter/frontend/widgets/entries.py", line 22, in <module>
    import dexter.backend.utilities as utilities
  File "/usr/lib/pymodules/python2.6/dexter/backend/utilities.py", line 32, in <module>
    from storm.expr import Or
  File "/usr/lib/python2.6/dist-packages/storm/expr.py", line 21, in <module>
    from decimal import Decimal
  File "/usr/lib/python2.6/decimal.py", line 3649, in <module>
    val = globals()[globalname]
KeyError: 'ROUND_CEiLiNG'