Insert Data To MSSQL Within Trigger From Oracle

I created a link from Oracle to SQL server.
There is a trigger with insert statment in Oracle side.
I got error message as follow when trigger is invoked:

SQL> insert into test1 values ('zerbra','brazi');
insert into test1 values ('zerbra','brazi')
*
ERROR at line 1:
ORA-02047: cannot join the distributed transaction in progress
ORA-06512: at "GGWEB.TRIGGER2", line 4
ORA-04088: error during execution of trigger 'GGWEB.TRIGGER2'

my simple trigger is as follows:
create or replace
TRIGGER TESTRI
AFTER INSERT ON TEST1
FOR EACH ROW
BEGIN
insert into test1@sqlserver (city,state) values ('what','nine');


END;