I get the exception attached as file after creating an entity. The mapping works on my development machine... a test server throws that exception. I've tried to search for eny differences in the tables but can't find any so far. The last time a similar error occured I was missing the versioned entry in the version table - these have been filled with the lowest revision available (the same way on my machine as on the test server). So I'm stuck... I have no access to the related source either... maybe this would help!