Problem/Bug Super Cube Brothers error

Im having a unusual problem with Super Cube Brothers (SCB) plugin, when people join the lobby and do /scb leave to leave the arena its says in chat "A internal error accrued while attempting to perform this command" , it still takes you out of the lobby but says this error and gives this in the logs: http://pastebin.com/z3pigsHr , i am using the un-updated version SCB 2.0 , and im not using 3.0 because when i do i have to reload the server before someone clicks a join sign for some reason. Any suggestions on whats wrong with the /scb leave and join signs on 3.0 (I kind of figured the join sign problem was because of it being not for 1.7.10 , but it is 1.7.9 which should work, any suggestions for my 2 problems would be great!