Oracle 12c Native network encryption

I am trying to enable oracle 12c native network encryption for a database setup in a RHel 7 environment. I have added these parameter to sqlnet.ora file in $ORACLE_HOME/network/admin on database server side

SQLNET.ENCRYPTION_SERVER = REQUESTED

SQLNET.ENCRYPTION_TYPES_SERVER = (AES256)

I have added this to the client side (testing with sql developer)

SQLNET.ENCRYPTION_CLIENT = REQUESTED

SQLNET.ENCRYPTION_TYPES_ = (AES256)

But when I run this sql

select network_service_banner 

   from v$session_connect_info i, v$session s 

   where 

   i.sid = s.sid and

   i.sid in (select distinct sid from v$mystat) ;

The output is not right