Connecting oracle 12c remotely

Question

I am pl/sql developer and does not have any experience in DBA. I installed an oracle linux virtual copy with oracle 12c preinstalled for learning and testing purposes. I have sql developer on my host machine and through it I connect to the DB on virtual as sys user, at this point everything is fine. But when I try connecting to the DB through SCOTT, HR or any other user that I created before it give me this error message:

An error was encountered performing the requested operation:

    ORA-01017: invalid username/password; logon denied
    01017. 00000 -  "invalid username/password; logon denied"
    *Cause:    
    *Action:
    Vendor code 1017

Notes:

1. I am very sure that username and password is correct.
2. This denied access appear only when I try connecting with DB from host machine with non-sys user.
3. when trying connecting through sqlplus on virtual machine all users connects without any problems.
4. I Unlock the user and changed it's password before trying.

How can I solve this problem

EDITED

connection properties:

connection_name : normal_user

username : SCOTT

pass : oracle

connection type : basic

role : default

hostname, port ,SID I am sure they are true.

when I execute this query select * from all_users where username = 'SCOTT' result is: USERNAME : SCOTT

USER_ID : 109

CREATED : 07-JUL-14

COMMON : NO

ORACLE_MAINTAINED : N