AIX 5.3 - Maximum login name length - Name is too long

# useradd aixadministrator
3004-694 Error adding "aixadministrator" : Name is too long.

# getconf LOGIN_NAME_MAX
9
# lsattr −El sys0 −a max_logname
max_logname 9 Maximum login name length at boot time True
# chdev −l sys0 −a max_logname=18
sys0 changed
# reboot