sqlplus works specifying the parameters but fails when using tnsnames.ora

Question

I've been turning google upside down and couldn't find an answer. I can connect to my oracle instance like this:

sqlplus 'myuser@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=msoracle.cnujcn8mkxea.us-east-1.rds.amazonaws.com)(PORT=1521))(CONNECT_DATA=(SID=ORCL)))'

But I can't make it work if I create a TNSNAMES.ORA at /usr/lib/oracle/12.1/client64/network/admin

ORCL=
(DESCRIPTION =
  (ADDRESS_LIST =
    (ADDRESS=(PROTOCOL=TCP)(HOST=msoracle.cnujcn8mkxea.us-east-1.rds.amazonaws.com)(PORT=1521))
  )
  (CONNECT_DATA=
  (SERVICE_NAME=ORCL)  -> I tried SID as well. No luck.
  )
)

I tried to

export ORACLE_SID=ORCL
export PATH=$PATH:$HOME/bin:/usr/lib/oracle/12.1/client64/bin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/oracle/12.1/client64/lib
export ORACLE_HOME=/usr/lib/oracle/12.1/client64
export TNS_ADMIN=$ORACLE_HOME/network/admin

And nothing. The following message always comes up:

ERROR:
ORA-12162: TNS:net service name is incorrectly specified

EDIT: This is the output of the tests in the comments:

[franklin@ip-10-148-17-253 client64]$ sqlplus myuser@ORCL

SQL*Plus: Release 12.1.0.2.0 Production on Fri Aug 5 10:13:39 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Enter password: 
ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified


Enter user-name: myuser
Enter password: 
ERROR:
ORA-12162: TNS:net service name is incorrectly specified


Enter user-name: ^C

Answer 1

I could fix the problem. I changed my TNS_NAMES.ORA removing ADDRESS_LIST and leaving like this:

ORCL=
(DESCRIPTION =
  (ADDRESS=(PROTOCOL=TCP)(HOST=msoracle.ccccc.us-east-1.rds.amazonaws.com)(PORT=1521))
  (CONNECT_DATA=
  (SID=ORCL)
  )
)

After I created a new file sqlnet.ora and added this:

NAMES.DIRECTORY_PATH = (TNSNAMES)

I also (just in case), renamed both files to lowercase:

[franklin@ip-10-148-17-253 admin]$ ls -ltr
total 8
-rw-r--r-- 1 root root 151 Aug  5 13:08 tnsnames.ora
-rw-r--r-- 1 root root  34 Aug  5 13:08 sqlnet.ora

So now I can connect just doing this:

sqlplus myuser/mypassword@ORCL