modifying Journal entry

If you cancel a committed Journal Entry , then try to modify and save any of the journal item you get the following error:

Client Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 180, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 1027, in onchange
    result = self.call_common(req, model, method, args, context_id=context_id)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 991, in call_common
    return self._call_kw(req, model, method, args, {})
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 1005, in _call_kw
    return getattr(req.session.model(model), method)(*args, **kwargs)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/openerplib/main.py", line 250, in proxy
    args, kw)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/openerplib/main.py", line 117, in proxy
    result = self.connector.send(self.service_name, method, *args)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 611, in send
    raise fault

Server Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 592, in send
    result = openerp.netsvc.dispatch_rpc(service_name, method, args)
  File "/usr/lib/pymodules/python2.7/openerp/netsvc.py", line 360, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/usr/lib/pymodules/python2.7/openerp/service/web_services.py", line 572, in dispatch
    res = fn(db, uid, *params)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 167, in execute_kw
    return self.execute(db, uid, obj, method, *args, **kw or {})
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 121, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/usr/lib/pymodules/python2.7/openerp/addons/audittrail/audittrail.py", line 495, in execute_cr
    return fct_src(cr, uid, model, method, *args)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 164, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/usr/lib/pymodules/python2.7/openerp/addons/account/account.py", line 1366, in onchange_line_id
    balance += (line[2]['debit'] or 0.00)- (line[2]['credit'] or 0.00)
KeyError: 'debit'

openerp versoin 6.1-20120313-003216

regards,