I wrote a little utility, which let's me import discussions from a different forum into SharePoint 2010. So far so good. It passed the "works on my machine" test successfully. Unfortunate I cannot say this about the client's machine.
For some very strange reason all discussions as well as all replies are being imported, but the ItemCount of the discussion stays at 0.
Looking at the ULS doesn't reveal any problems.
Has anyone any kind of hint?