I'm migrating a Small Business Server 2003 to Small Business Server 2008 and I hit a problem. The source server is in English and the target server is in Swedish. You need to run sourcetool.exe to prepare the source server AD Schema. This tools fails if you take the tools folder from a Swedish media. (or any other than the language of the source server). The error you get is UnableToModifyError(6)

I found the solution after a few hours of Google. Change the name of the folder called sv-se located in the adprep folder. In my case I change from sv-se to en-us. Then run the sourcetool.exe again with success.

Big thanks to this blog and this thread. Saved my day!