[LAU] Allocating and setting up memory lock and real time group add terminal errors

hey all firstly when i go to add my self to the real time group with these commands groupadd realtime usermod -a -G realtime sound-warrior i get these errors from terminal sound-warrior@the-megga-machine:~$ sound-warrior@the-megga-machine:~$ groupadd realtime groupadd: cannot lock /etc/group; try again later. sound-warrior@the-megga-machine:~$ usermod -a -G realtime sound-warrior usermod: group 'realtime' does not exist sound-warrior@the-megga-machine:~$ does any one know what these errors mean and how to solve the problem? secondly how do you set up and use memory allocation and memory locking for audio work? Your help with this problem and question would be most welcome. Kind regards trahern.