Hi 

when i try to install a module i get this error : KeyError: 'fold' ! 

but i cant see the source of the error ! 

can someone help me please 

the error log is bellow : 

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 659, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 696, in dispatch
    result = self._call_function(**self.params)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 332, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/service/model.py", line 118, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 325, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 975, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 525, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web/controllers/main.py", line 901, in call_button
    action = self._call_kw(model, method, args, {})
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web/controllers/main.py", line 889, in _call_kw
    return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/module/module.py", line 460, in button_immediate_install
    return self._button_immediate_function(cr, uid, ids, self.button_install, context=context)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/module/module.py", line 535, in _button_immediate_function
    registry = openerp.modules.registry.RegistryManager.new(cr.dbname, update_module=True)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 386, in new
    openerp.modules.load_modules(registry._db, force_demo, status, update_module)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 378, in load_modules
    loaded_modules, update_module, models_to_check)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 271, in load_marked_modules
    perform_checks=perform_checks, models_to_check=models_to_check
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 154, in load_module_graph
    registry.setup_models(cr, partial=True)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 203, in setup_models
    model._setup_complete(cr, SUPERUSER_ID)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 354, in old_api
    result = method(recs, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3097, in _setup_complete
    field.setup_triggers(self.env)
  File "/usr/lib/python2.7/dist-packages/openerp/fields.py", line 1857, in setup_triggers
    self._add_trigger(env, arg[0], self)
  File "/usr/lib/python2.7/dist-packages/openerp/fields.py", line 628, in _add_trigger
    field = model._fields[name]
KeyError: 'fold'