jack controll problem "Your system has an audio group, but you are not a member of it."

Hello ladies and gentleman!

as i wrote in the subject when i start jack control it says:

15:37:13.353 JACK wurde mit PID = 8755 gestartet.
Your system has an audio group, but you are not a member of it.
Please add yourself to the audio group by executing (as root):
usermod -a -G audio (null)
After applying these changes, please re-login in order for them to take effect.
You don't appear to have a sane system configuration. It is very likely that you
encounter xruns. Please apply all the above mentioned changes and start jack again!

but when type in my terminal: "fgrep -ie 'audio' /etc/group"
it says "audio:x:29:pulse,hannes" (hannes is username i think :-) )

so.. i really have no idea what to do...