traceback when i try to open a journal item

[Aline (OpenERP)]

- create some invoices and payments (reconcile them)
- go to Accounting/Journal Entries/Journal Entries
- click on a line :

Client Traceback (most recent call last):
  File "/home/aline/source/web/trunk/addons/web/common/http.py", line 180, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/home/aline/source/web/trunk/addons/web/controllers/main.py", line 784, in get
    return self.do_get(req, model, ids, fields)
  File "/home/aline/source/web/trunk/addons/web/controllers/main.py", line 806, in do_get
    records = Model.read(ids, fields, req.session.eval_context(req.context))
  File "/home/aline/source/web/trunk/addons/web/common/session.py", line 195, in eval_context
    return ccontext.evaluate(ctx)
  File "/home/aline/source/web/trunk/addons/web/common/nonliterals.py", line 267, in evaluate
    final_context.update(context_to_eval.evaluate(ctx))
  File "/home/aline/source/web/trunk/addons/web/common/nonliterals.py", line 267, in evaluate
    final_context.update(context_to_eval.evaluate(ctx))
  File "/home/aline/source/web/trunk/addons/web/common/nonliterals.py", line 187, in evaluate
    raise ValueError('Error during evaluation of this context: "%s", message: "%s"' % (self.get_context_string(), e.message))
ValueError: Error during evaluation of this context: "{'lines':line_id ,'journal':journal_id }", message: "name 'line_id' is not defined"