CONNECTION REJECTED:unacceptable nickname

OLD NAME - ZURG_STF
NEW NAME -MADARA_UCHIHA_STF
yesterday i send request change my name and today admin accepted to change my name ZURG_STF to MADARA_UCHIHA_STF.
then i try to reenter the server again -->https://youtu.be/tDETc8sm7qc
i think problem is causes because of MADARA_UCHIHA_STF has 21 letters or maybe i made a spelling mistake when changing my name,pls check that too.......

name changed back to ZURG_STF. You can join now.