Oracle Database Discussions

Hello,
I’m trying to make a communication between oracle and SQL server 2005.
I use oracle 10g E.E Release 10.2.0.3.0 and the transparent gateway for SQL server 10201_gatway_win32.zip.
Install:
The oracle database is installed into a server named ss-serv. This server has two partition disk C and E. Oracle database is installed in E and the gateway in C. There is already a database (instance) running in the oracle home (in E).
I configured the gateway as described into: http://download.oracle.com/docs/cd/B...3/conf_sql.htm.
In sql server 2005, there is a database running named ClientTricks.
I created a user named Avogadro with a login.
In the partition C where the gateway is installed, the file inittg4msql.ora is like this:
HS_FDS_CONNECT_INFO= ss-serv. ClientTricks

The file sqlnet.ora where the gateway is installed is configured like this:
SQLNET.AUTHENTIFICATION_SERVICES=(NTS)
NAMES.DIRECTORY_PATH = (TNSNAMES, EZCONNECT)

I configured the listener that is in the C partition where the gateway is installed, and the tnsnames that is in the oracle database in E partition disk like this:
Listener :
LISTENER=
(ADDRESS=
(PROTOCOL=TCP)
(HOST=ss-serv)
(PORT=1521))

SID_LIST_LISTENER=
(SID_LIST=
(SID_DESC=
(SID_NAME=tg4msql)
(ORACLE_HOME=C:\oracle\product\10.2.0\tg_1)
(PROGRAM=tg4msql)
)
)
tnsnames:

mytg4msql=
(DESCRIPTION=
(ADDRESS=
(PROTOCOL=TCP)
(HOST=ss-serv)
(PORT=1521)
)
(CONNECT_DATA=
(SID=tg4msql))
(HS=OK))

After edited the listener, I stop and start the listener for the transparent gateway from administrative tools in the services.
Then, connected in oracle (in a database named fakeclient) I created a database link in sqlplus.The the dblink were created, but when I tried to querry some data from ClientTricks by executing the following instructions:
select * from s_client@dblink
i got this fatal and terrible error :
ora-12154 TNS:could not resolve the connect identifier specified
I verified all my procedure and stapes, all seems to be good. I did a tnsping of mytg4msql

I got this error in the command prompt:TNS-03505 fail to resolve name

Could someone help me ?
Sorry for my English ,I’m French

best regards