ORA-26713 Streams Apply Error And Gateway

My setup is following:

CODEhost22 (Oracle Linux 5.9)               |  host30 (Windows XP) with SQL Server Express 2008
         DB22       | Gateway to MSSQL  |                 DB30
Local       Local   |                   |                    
Capture --> Apply ------> Gateway -----------------> DUMMYUSR.DUMMYTBL      
Process     Process |                   |

Capture process on DB22 captures changes made to local DUMMYUSR.DUMMYTBL table, enqueues it to capture queue and propagates to apply queue for local apply process, which, using database link DB30 supposed to apply these changes to table DUMMYUSR.DUMMYTBL on remote SQL Server database DB30.

The problem is that when apply process is executing transaction, it aborts with error:
QUOTE ORA-26713: remote object does not exists or is inaccessible.
ORA-26712: remote object is "DUMMYUSR"."DUMMYTBL"@"DB30".
In trace log I can see the following message:
QUOTE kniNoPrimaryKeyError: ORA-26713, remote obj doesn't exist,
DUMMYUSR.DUMMYTBL@DB30
[code]...

what can cause ORA-26713 error of apply process applying changes to SQL Server database through Oracle Database Gateway, if object to be modifyed exists and accessible from Oracle database for strmadmin user?

By the way, database link and tables were created with following commands: CODEDB22(Oracle): (connected as strmadmin) create database link DB30 connect to "dummyusr" identified by "dummypwd" using 'DB30';

DB22(Oracle): (connected as dummyusr)
create table DUMMYTBL (no number, name char(6), ddate date, payload varchar2(2013));
DB30(MSSQL): (connected as dummyusr)
create schema DUMMYUSR authorization dummyusr;
create table DUMMYUSR.DUMMYTBL (no float(53), name char(6), ddate datetime2(0), payload varchar(2013));