SQL & PL/SQL :: Changes In Remote Database

I want to update my table base on changes in a column of a table from remote database automatically. I just want to pick some updated column then update to my own. i have made a trigger but failed.

CREATE OR REPLACE
TRIGGER TG_UPD_ID
after update OF STUD_ID on STUDENT@SCHOOLDB
for each row
begin

update MARKS set ID_ST = :new.STUD_ID where STUDID_STUDENT = :old.IDS;

end;

Error report:
ORA-02021: DDL operations are not allowed on a remote database
02021. 00000 - "DDL operations are not allowed on a remote database"
*Cause: An attempt was made to use a DDL operation on a remote database.

For example, "CREATE TABLE tablename@remotedbname ...".

*Action: To alter the remote database structure, you must connect to the remote database with the appropriate privileges.