Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/view/list.py", line 972, in __sig_switch
    if not self.screen.row_activate() and self.children_field:
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 428, in default_row_activate
    }, context=self.context.copy(), warning=False)
  File "/usr/local/lib/python2.7/dist-packages/tryton/action/main.py", line 166, in exec_keyword
    Action._exec_action(action, data, context=context)
  File "/usr/local/lib/python2.7/dist-packages/tryton/action/main.py", line 129, in _exec_action
    context_model=action['context_model'])
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/window.py", line 34, in create
    context_model=context_model)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/form.py", line 117, in __init__
    context_model=context_model)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 147, in __init__
    self.switch_view()
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 454, in switch_view
    self.load_view_to_load()
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 475, in load_view_to_load
    self.add_view_id(view_id, view_type)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 488, in add_view_id
    return self.add_view(view)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/screen/screen.py", line 513, in add_view
    view = View.parse(self, xml_dom, view.get('field_childs'))
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/view/__init__.py", line 47, in parse
    return ViewTree(screen, root, children_field)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/view/list.py", line 289, in __init__
    self.parse(xml)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/view/list.py", line 329, in parse
    self._parse_field(node)
  File "/usr/local/lib/python2.7/dist-packages/tryton/gui/window/view_form/view/list.py", line 339, in _parse_field
    field = group.fields[name]
KeyError: 'category'