version 6.1: project , project plan

via Project > Reporting > Projects actio task leveling without select project
extract error:

Traceback (most recent call last):
  File "/trytond/wsgi.py", line 117, in dispatch_request
    return endpoint(request, **request.view_args)
  File "/trytond/protocols/dispatcher.py", line 48, in rpc
    request, database_name, *request.rpc_params)
  File "/trytond/wsgi.py", line 84, in auth_required
    return wrapped(*args, **kwargs)
  File "/trytond/protocols/wrappers.py", line 159, in wrapper
    return func(request, pool, *args, **kwargs)
  File "/trytond/protocols/dispatcher.py", line 181, in _dispatch
    result = rpc.result(meth(*c_args, **c_kwargs))
  File "/trytond/wizard/wizard.py", line 314, in execute
    return wizard._execute(state_name)
  File "/trytond/wizard/wizard.py", line 345, in _execute
    result = self._execute(transition())
  File "/trytond/modules/project_plan/work.py", line 653, in transition_leveling
    self.record.create_leveling()
AttributeError: 'NoneType' object has no attribute 'create_leveling'

Fault: 'NoneType' object has no attribute 'create_leveling'