When first time i tried to create database, i constantly got error from jsampler, from which it is not clear, that it needs to be formated.
I don't report it as jsampler bug, because it is not clear, what is usefulness from unformatted database.
Please check if this bug still persists with latest SVN version. There had been a change to the instruments DB implementation recently, which fixed undefined behavior on instruments DB operations.
I consider this bug being fixed with latest SVN version of LinuxSampler. There had been several fixes to the instruments DB backend which should fixed this issue.