Error: "ORA-01031 insufficient privileges" when trying to connect in SQLPLUS. (4268084)

Trying to use the  Oracle User Wizard to set up a Spotlight user in Oracle database.

When entering credentials for user/password with DBA privileges I get the  error "ORA-01017: Invalid Username / Password" in the Oracle User Wizard .

When trying to connect with the same DBA privileges in SQL*PLUS to  database  A  I  get :

command: sqlplus sys/<sys_password> as sysdba => WORKED
command: sqlplus sys/<sys_password>@A as sysdba => FAILED

The failed connection returns error: "ORA-01031: insufficient privileges"

However both login commands worked fine when trying to connect to database B.

N:B: Error: "ORA-01031: insufficient privileges" was responsible for the Oracle User Wizard setup returning error "ORA-01017: Invalid Username / Password".