How could I use "Linked Server" from SSMS IDE to connect the Oracle server database with "SYSDBA"?

I've tried many methods as following to show you what I did right now:
Oracle client connect to Oracle Server data:

SSMS connect to Oracle Server data:

More testing information
I also use "SQLPLUS" to check tnsnames.ora the file is okay or not but the answer is as following

1. sqlplus SYS/Oradoc_db1@DBNAME as SYSDBA <-- is okay
2. sqlplus SYS/Oradoc_db1@DBNAME <-- Error