Have a look on this thread: http://fusesource.com/forums/thread.jspa?threadID=3392&tstart=0
Another user was experiencing a similar behavior and he was able to get everything working. Basically, change the system.properties (under $SMX_HOME/etc) file (add karaf.admin.role=admin) and then remove the data directory under $SMX_HOME directory and then restart ServiceMix (FUSE ESB).
Just keep in mind that you may be purging the data already there in the FUSE ESB but that should fix the issue.
Hope this helps,