I have a profile that limits the SESSIONS_PER_USER to 1 but it does not seem to be working

CREATE PROFILE PROF_USER
LIMIT SESSIONS_PER_USER 1
CPU_PER_SESSION DEFAULT
CPU_PER_CALL DEFAULT
CONNECT_TIME DEFAULT
IDLE_TIME DEFAULT
LOGICAL_READS_PER_SESSION DEFAULT
LOGICAL_READS_PER_CALL DEFAULT
COMPOSITE_LIMIT DEFAULT
PRIVATE_SGA DEFAULT
FAILED_LOGIN_ATTEMPTS 5
PASSWORD_LIFE_TIME 90
PASSWORD_REUSE_TIME 365
PASSWORD_REUSE_MAX UNLIMITED
PASSWORD_LOCK_TIME DEFAULT
PASSWORD_GRACE_TIME 0
PASSWORD_VERIFY_FUNCTION F_VERIFY_PASSWORD
/

The user has this profile for their default.

Any ideas why it is not working?