error submitting grade to a skill in a cando project

Hi.
I resently had to reinstall schooltool on our server. I chose to import the old dattabase, but now i get an errormessage when I make a new project in cando, then add skills in that project, and try to grade that skill. I can however grade skills in the skillset view in can do. How can i fix this? This happend a few times when I had the old versoin, but I fixed it by exporting the school, then clear the database, and import the xml file again. I cant do that now, because then we loose all the informasjon we have registerd on the students.

Here is the errormessage.

 Tjenerfeil

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Unntak
AttributeError: 'NoneType' object has no attribute '__parent__'

Sporingsdata

File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 132, in publish
  result = publication.callObject(request, obj)
File "/usr/lib/python2.7/dist-packages/zope/app/publication/zopepublication.py", line 205, in callObject
  return mapply(ob, request.getPositionalArguments(), request)
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 107, in mapply
  return debug_call(obj, args)
Extra information: <schooltool.skin.flourish.zcml_content.ProjectsGradebookOverview_index.html object at 0x7f675d8fc490>
File "/usr/lib/python2.7/dist-packages/zope/publisher/publish.py", line 113, in debug_call
  return obj(*args)
File "/usr/lib/python2.7/dist-packages/schooltool/skin/flourish/page.py", line 98, in __call__
  self.update()
File "/usr/lib/python2.7/dist-packages/schooltool/gradebook/browser/gradebook.py", line 1167, in update
  GradebookOverview.update(self)
File "/usr/lib/python2.7/dist-packages/schooltool/gradebook/browser/gradebook.py", line 656, in update
  student['object'], activity, cell_score_value, evaluator)
File "/usr/lib/python2.7/dist-packages/schooltool/cando/gradebook.py", line 102, in evaluate
  equivalent = self.filterEquivalent(activity.findAllEquivalent())
File "/usr/lib/python2.7/dist-packages/schooltool/cando/gradebook.py", line 97, in filterEquivalent
  equivalent)
File "/usr/lib/python2.7/dist-packages/schooltool/cando/gradebook.py", line 96, in <lambda>
  lambda e: ISection(e.__parent__, None) is self.section,
File "/usr/lib/python2.7/dist-packages/zope/component/hooks.py", line 119, in adapter_hook
  return siteinfo.adapter_hook(interface, object, name, default)
File "/usr/lib/python2.7/dist-packages/schooltool/cando/gradebook.py", line 266, in getCourseSkillSetSection
  return worksheet.__parent__.__parent__

Modules

schooltool 2.8.5 (/usr/lib/python2.7/dist-packages)

schooltool.cando 2.8.2 (/usr/lib/python2.7/dist-packages)

schooltool.gradebook 2.8.4.1 (/usr/lib/python2.7/dist-packages)

schooltool.intervention 2.7.0 (/usr/lib/python2.7/dist-packages)

schooltool.lyceum.journal 2.8.2.1 (/usr/lib/python2.7/dist-packages)
Runtime

Python 2.7.6 (default, Jun 22 2015, 17:58:13) [GCC 4.8.2]

Linux schooltool 3.13.0-83-generic #127-Ubuntu SMP Fri Mar 11 00:25:37 UTC 2016 x86_64 x86_64

Filesystem encoding ANSI_X3.4-1968, preferred ANSI_X3.4-1968